Prognostic and predictive significance of p53, EGFr,Ki-67 in larynx preservation treatment

Background

The optimal management of advanced laryngeal and hypopharyngeal cancers (L&HC) must involve consideration of both survival and functional effect of the given treatment approach. Despite over two decades of investigations of several treatment options, including surgery, radiotherapy, chemotherapy or some combinations thereof, little consensus exists as to which treatment offers the best survival, together with functional speech and swallowing.

Aim

To determine predictive and prognostic value of p53, EGFr, Ki-67 in patients with advanced laryngeal and hypopharyngeal cancer, treated with larynx preservation intent.

Materials and methods

Thirty-three patients received 2–3 cycles of induction chemotherapy (ICHT) consisting of cisplatin and fluoruracil and underwent subsequent radical radiotherapy. Immunohistochemical analyzes of p53, EGFr and Ki-67 were performed.

Results

Response to ICHT was obtained in 24 patients (75%). Better response to ICHT was correlated only with EGFr expression (p = 0.04, RR = 1.91). The 5-year loco-regional control (LRC) and disease-specific survival (DSS) rates were 48% and 57%, respectively. The 5-year larynx preservation rate was 68% in responders to ICHT compared to 21% in non-responders (p = 0.02). It was also higher in patients without EGFr expression (but not significantly, p = 0.43).

Conclusion

Lack of EGFr expression is a favorable predictive factor for response to ICHT. Neither p53 nor Ki-67 have predictive and prognostic value in larynx preservation treatment.     

Neoadjuvant oral vs. infusional chemoradiotherapy on locally advanced rectal cancer: Prognostic factors

Aim

To evaluate the prognostic factors and impact on survival of neoadjuvant oral and infusional chemoradiotherapy in patients with locally advanced rectal cancer.

Background

There is still no definitive consensus about the prognostic factors and the impact of neoadjuvant chemoradiotherapy on survival. Some studies have pointed to an improvement in overall survival (OS) and progression-free survival (PFS) in patients with tumor downstaging (TD) and nodal downstaging (ND).

Materials and methods

A set of 159 patients with LARC were treated preoperatively. Group A – 112 patients underwent concomitant oral chemoradiotherapy: capecitabine or UFT + folinic acid. Group B – 47 patients submitted to concomitant chemoradiation with 5-FU in continuous infusion. 63.6% of patients were submitted to adjuvant chemotherapy.

Results

Group A: pathologic complete response (pCR) – 18.7%; TD – 55.1%; ND – 76%; loco-regional response – 74.8%. Group B: pCR – 11.4%; TD – 50%; ND – 55.8%; LRR – 54.5%. The loco-regional control was 95.6%. There was no difference in survival between both groups. Those with loco-regional response had better PFS.

Conclusions

Tumor and nodal downstaging, loco-regional response and a normal CEA level turned out to be important prognostic factors in locally advanced rectal cancer. Nodal downstaging and loco-regional response were higher in Group A. Those with tumor downstaging and loco-regional response from Group A had better OS. Adjuvant chemotherapy had no impact on survival except in those patients with loco-regional response who achieved a higher PFS.     

Impact of neoadjuvant chemoradiation on pathologic response and survival of patients with locally advanced rectal cancer

Background

The impact of neoadjuvant chemotherapy (CT) and radiotherapy (RT) on overall survival (OS) has been controversial. Some studies have pointed to an improvement in OS and disease-free survival (DFS) in patients with pathologic complete response (pCR).

Aim

To evaluate the therapeutic response and impact on survival of preoperative RT, alone or combined with CT, in patients with locally advanced rectal cancer (LARC).

Materials and methods

A set of 132 patients with LARC were treated preoperatively. GROUP 1: RT alone, 19 patients. GROUP 2: RT and concomitant oral CT (Capecitabine or UFT + leucovorin), 68 patients. GROUP 3: RT and concomitant CT with 5-FU in continuous infusion, 45 patients. 58.2% of patients were submitted to adjuvant CT.

Results

GROUP 1: no pCR, tumoral downstaging was 26.7%. GROUP 2: pCR in 16.9%; tumoral downstaging was 47.7%. GROUP 3: pCR in 11.9%; tumor downstaging was 52.4%. The loco-regional control (LRC) was 95%. The 5-year OS (p = 0.038) and DFS (p = 0.05) were significantly superior in patients treated with CT + RT. Patients with pCR had a significant increase on DFS (p = 0.019). Patients cT3–4 that had a tumoral downstaging to ypT0–2, showed an increase on DFS, OS and LRC.

Conclusions

CT combined with RT has increased tumoral response and survival rate. Nodal downstaging and pCR were higher in the GROUP 2. The 5-year OS and DFS were significantly superior in CT + RT arms. Patients with pathologic response showed a better DFS. Adjuvant CT had no impact on LRC, DFS nor on OS.     

The effect of lymphadenectomy and radiotherapy on recurrence and survival in endometrial carcinoma. Experience in a population reference centre

Aim

To evaluate the effect of lymphadenectomy and/or radiotherapy on recurrence and survival patterns in endometrial carcinoma (EC) in a radiotherapy reference centre population.

Material and Methods

A retrospective population-based review was conducted on 261 patients with stages I–III EC. Univariate and multivariate analyses were carried out. Both recurrence and survival were analysed according to patient age, FIGO stage, tumour size, myometrial invasion, tumour grade, lymphadenectomy, external beam irradiation (EBI), and brachytherapy (BT).

Results

Median age: 64.8 years. Median follow-up: 151 months. The following treatments were administered: surgery, 97.32%; lymph-node dissection, 54.4%; radiotherapy, 162 patients (62%) (EBI and BT: 64.1%, BT alone: 30.2%, EBI alone: 5.6%).Twenty-six patients (9.96%) suffered loco-regional recurrence, whilst 27 (10.34%) suffered distant failure. The 5-year overall survival (OS) for all stages was 80.1%. The 5-year disease free survival (DFS) was 92.1% for all patients. The 10-year DFS was 89.9%.The independent significant prognostic factors for a good outcome identified through the multivariate analysis were: age <75 years (p = 0.001); tumour size ≤2 cm (p = 0.003); myometrial invasion ≤50% (p = 0.011); lymphadenectomy (p = 0.02); EBI (p = 0.001); and BT (p = 0.031).Toxicity occurred in 114 of the 162 patients who received radiotherapy (70.5%). The toxicity was mainly acute, and late in only 28.3% (n = 45) of cases. The majority experienced G1-2 toxicity, and only 3% of patients experienced G3 late toxicity (5/162).

Conclusions

Our results suggest that age <75 years, tumour size ≤2 cm, myometrial invasion ≤50%, lymphadenectomy, EBI, and BT, are predictors of a good outcome in EC.     

Postoperative radiotherapy in prostate cancer: Analysis of prognostic factors in a series of 282 patients

Aim

To assess the outcomes of patients treated with postoperative RT in relation to the possible prognostic factors.

Background

Postoperative radiotherapy (RT) has been proved to reduce the risk of biochemical recurrence in high-risk prostate cancer patients. Baseline prostate specific antigen (PSA), pathological Gleason score (GS), positive surgical margins, nodal status and seminal vesicle invasion are independent predictors of biochemical relapse.

Materials and methods

The clinical records of 282 patients who underwent postoperative RT were retrospectively reviewed. The prognostic value of postoperative PSA, preoperative risk class, nodal status, pathological GS, margins status, and administration of hormonal therapy (HT) was analyzed.

Results

Postoperative RT was delivered with a median dose to the prostatic fossa of 66 Gy (range 50–72) in 1.8–2 Gy/fraction. Median follow-up was 23.1 months (range 6–119). Five-year actuarial biochemical disease-free survival (bDFS) and overall survival rates were 76% and 95%, respectively. Higher bDFS was found for patients with postoperative PSA <0.02 ng/ml (p = 0.03), low preoperative risk class (p = 0.01), pN0 (p = 0.003), GS 4–6 (p = 0.0006), no androgen deprivation therapy (p = 0.02), and irrespective of surgical margin status (p = 0.10). Multivariate analysis showed that postoperative PSA and Gleason score had a significant impact on bDFS (p = 0.039 and p = 0.05, respectively).

Conclusions

Postoperative RT with a dose of 66 Gy offers an acceptable toxicity and an optimal disease control after radical prostatectomy in patients with different risk features. A postoperative PSA >0.02 ng/ml could be considered as a prognostic factor and a tool to select patients at risk for progression.     

Role of radiation therapy in the multidisciplinary management of Ewing's Sarcoma of bone in pediatric patients: An effective treatment for local control

Background

Radiotherapy (RT) plays an important role in the multidisciplinary management of Ewing''s Sarcoma (ES), especially in unresectable cases.

Aim

Assessment of efficacy of RT in terms of local control in pediatric patients with primary ES of bone.

Materials and methods

Thirty-six patients younger than 17 years old with ES treated with combined RT and chemotherapy with (N = 14) or without (N = 22) prior surgery from 1981 to 2008 were retrospectively reviewed. Since 1995, they were all treated according to the Spanish Society of Pediatric Oncology protocol (55.5% cases). Those patients received vincristine, ifosfamide, doxorubicin and etoposide. The TNM classification was as follows: 17 T1, 18 T2 and 1 T3; 36 N0; 29 M0, 5 M1a and 2 M1b. Analysis was stratified by treatment: definitive RT or pre/postoperative RT.

Results

The 36 patients (21 male; 15 female) had a median age of 10 years (range 2–17 years). Median follow-up of living patients was 105 months. The 2-year local control (LC) rate for all patients was 88%. Five-year LC rates for patients treated with definitive and pre/postoperative RT were 91% and 86%, respectively. Two-year overall survival and disease-free survival rates for all patients were 68% and 66%, respectively. Low phosphatase alkaline levels and local and distant recurrences were significantly predictive of worse prognosis (P = 0.021, P = 0.011, P = 0.007, respectively).

Conclusion

Radiotherapy with and without surgery is a highly effective local treatment option in the multidisciplinary management of ES in pediatric patients.     

Interleukin-6 (IL-6) and C-reactive protein (CRP) concentration prior to total nephrectomy are prognostic factors in localized renal cell carcinoma (RCC)

Background

Radical nephrectomy is the gold standard for treatment of renal cell carcinoma (RCC), but even for localized disease the survival rates are still unsatisfactory. Identification of prognostic factorsl is the basis for future treatment strategies for an individual patient.

Aim

The aim of our study was to assess the usefulness of the concentration of IL-6 and CRP as prognostic factors in patients after nephrectomy due to localized RCC.

Materials and methods

Our prospective study included 89 patients (55 men and 34 women) who had been surgically treated for RCC. The examined group included patients with localized advanced disease (from T1 to T3) with no metastases in lymph nodes (N0), and with no distant metastases (M0). All patients had blood samples drawn three times during the study (one day before surgery, six days after surgery and 6 months after surgery) to evaluate the concentration of CRP and IL-6. In each patient RCC of the kidney was removed during radical nephrectomy. Statistical analysis was conducted using statistica v.7.0.

Results

Statistically significant relationships were found between the concentration of CRP before the operation and OS (p = 0.0001). CRP concentration at baseline was statistically significantly correlated with CSS (p = 0.0004). The level of IL-6 assessed before the surgery was significantly correlated with survival times such as OS (p = 0.0096) and CSS (p = 0.0002). The concentration of IL-6 and CRP measured 6 days after surgery and 6 months after surgery were not statistically significantly correlated with survival times.

Conclusions

Results of our study showed that elevated levels of IL-6 and CRP in peripheral blood before surgery of RCC were correlated with worse OS and CSS.     

Meta-Analysis of Randomised Clinical Trials Comparing Idarubicin + Cytarabine with Daunorubicin + Cytarabine as the Induction Chemotherapy in Patients with Newly Diagnosed Acute Myeloid Leukaemia

Background

To determine whether the use of idarubicin+cytarabine (IA) is more effective than the use of daunorubicin+cytarabine (DA) as induction chemotherapy for patients with newly diagnosed acute myeloid leukaemia.

Methods

A computer-based search was performed. Randomised trials comparing IA with DA as induction therapy for newly diagnosed AML were included in this meta-analysis. The primary outcome of interest for our analysis was survival (disease-free survival, event-free survival and overall survival); the secondary endpoint was complete remission.

Results

Ten trials with 4,060 patients were eligible for this meta-analysis. Our pooled results suggest that IA is associated with a significant advantage in CR (RR = 1·23; 95% CI = 1·07–1·41, p = 0.004), EFS (HR = 0·64; 95% CI = 0·45–0·91, p = 0.013), and OS (HR = 0·88; 95% CI = 0·81–0·95, p = 0.02) but not in DFS (HR = 0·90; 95% CI = 0·80–1·00, p = 0.06). In the subgroup analysis, age had a significant interaction with OS and CR benefits.

Conclusion

Our analysis indicated that IA could improve the duration of overall survival compared to DA as induction therapy for young patients with newly diagnosed AML. Further study is needed to determine whether IA can produce clinical benefits in selected genetic or molecular subgroups of young AML patients.     

High survival rate of 43% in out-of-hospital cardiac arrest patients in an optimised chain of survival

Aims

Survival to hospital discharge after out-of-hospital cardiac arrest (OHCA) varies widely. This study describes short-term survival after OHCA in a region with an extensive care path and a follow-up of 1 year.

Methods

Consecutive patients ≥16 years admitted to the emergency department between April 2011 and December 2012 were included. In July 2014 a follow-up took place. Socio-demographic data, characteristics of the OHCA and interventions were described and associations with survival were determined.

Results

Two hundred forty-two patients were included (73 % male, median age 65 years). In 76 % the cardiac arrest was of cardiac origin and 52 % had a shockable rhythm. In 74 % the cardiac arrest was witnessed, 76 % received bystander cardiopulmonary resuscitation and in 39 % an automatic external defibrillator (AED) was used. Of the 168 hospitalised patients, 144 underwent therapeutic procedures. A total of 105 patients survived until hospital discharge. Younger age, cardiac arrest in public area, witnessed cardiac arrest, cardiac origin with a shockable rhythm, the use of an AED, shorter time until return of spontaneous circulation, Glasgow Coma Scale (GCS) ≥13 during transport and longer length of hospital stay were associated with survival. Of the 105 survivors 72 survived for at least 1 year after cardiac arrest and 6 patients died.

Conclusion

A survival rate of 43 % after OHCA is achievable. Witnessed cardiac arrest, cardiac cause of arrest, initial cardiac rhythm and GCS ≥13 were associated with higher survival.     

Measurement and comparison of head scatter factor for 7 MV unflattened (FFF) and 6 MV flattened photon beam using indigenously designed columnar mini phantom

Aim

To measure and compare the head scatter factor for 7 MV unflattened and 6 MV flattened photon beam using a home-made designed mini phantom.

Background

The head scatter factor (Sc) is one of the important parameters for MU calculation. There are multiple factors that influence the Sc values, like accelerator head, flattening filter, primary and secondary collimators.

Materials and methods

A columnar mini phantom was designed as recommended by AAPM Task Group 74 with high and low atomic number material for measurement of head scatter factors at 10 cm and d_max dose water equivalent thickness.

Results

The Sc values measured with high-Z are higher than the low-Z mini phantoms observed for both 6MV-FB and 7MV-UFB photon energies. Sc values of 7MV-UFB photon beams were smaller than those of the 6MV-FB photon beams (0.6–2.2% (Primus), 0.2–1.4% (Artiste) and 0.6–3.7% (Clinac iX (2300CD))) for field sizes ranging from 10 cm × 10 cm to 40 cm × 40 cm. The SSD had no influence on head scatter for both flattened and unflattened beams. The presence of wedge filters influences the Sc values. The collimator exchange effects showed that the opening of the upper jaw increases Sc irrespective of FF and FFF.

Conclusions

There were significant differences in Sc values measured for 6MV-FB and unflattened 7MV-UFB photon beams over the range of field sizes from 10 cm × 10 cm to 40 cm × 04 cm. Different results were obtained for measurements performed with low-Z and high-Z mini phantoms.     

Hyperfractionated high-dose rate brachytherapy in the treatment of oral tongue cancer

Background

Low-dose rate brachytherapy is a well established treatment modality of oral cancer. Data about high-dose rate (HDR) brachytherapy are still sparse with various fractionation schedules and heterogeneous results.

Aim

The aim of our retrospective study was to evaluate the results of HDR brachytherapy with doses of 3 Gy twice daily.

Patients and methods

Twenty patients with squamous cell tongue cancer were treated in the years 2001–2009 by exclusive HDR BT 18 × 3 Gy twice daily. The plastic tube technique was used. Median follow up was 47 months (7.8–118) since brachytherapy.

Results

The local and locoregional control was 85% and 68%, respectively. Bone necrosis developed in one case treated without mandibular shielding and soft tissue necrosis in 2 cases.

Conclusion

It can be concluded that HDR brachytherapy with 18 × 3 Gy twice daily is safe with promising local control. The risk of nodal recurrences is substantial.     

Characteristics of long-term survivors of brain metastases from lung cancer

Background and aim

Long-term survival of lung cancer patients with brain metastases (BM) is very rare. Our aim is to report the characteristics of patients who survived for at least three years after a BM diagnosis.

Materials and methods

Nineteen lung cancer patients who had survived ≥3 years after a BM diagnosis were identified in our database. Seven (37%) had undergone whole-brain radiotherapy (WBRT) only, five (26%) BM surgery + WBRT, three (16%) BM surgery + WBRT + BM radiosurgery, and four (21%) no WBRT (one, surgery; one, radiosurgery; two, BM surgery + radiosurgery). Their characteristics were compared with historical data for 322 lung cancer patients with BM (control group, CG), who had received WBRT between 1986 and 1997.

Results

Median survival from BM in long survivors group was 73 months (in CG – 4 months). Characteristics comparison: median age 55 vs. 58 (CG), p = 0.16; female sex 68% vs. 28% (CG), p = 0.003; RTOG/RPA class 1 – 75% vs. 13% (CG), p = 0.00001; adenocarcinoma histology 84% vs. 24% (CG), p < 0.00001; control of primary tumor 95% vs. 27% (CG), p < 0.00001; extracranial metastases 0 vs. 26% (CG), p = 0.01; single BM 63% vs. 9% (CG), p = 0.00001; surgery of BM 53% vs. 14% (CG), p = 0.00001.

Conclusions

Beside prognostic factors already recognized as favorable in patients with BM, the adenocarcinoma histology and female sex were prevalent in long-term survivors of BM from lung cancer.     

Unintended irradiation of internal mammary chain – Is that enough?

Aim

To evaluate the unintentional coverage of the internal mammary chain (IMC) with tangential fields irradiation to the breast, and its relation with the type of surgery employed.

Background

The dose distribution in regions adjacent to the treatment targets (mammary gland or chest wall), with incidental irradiation of the IMC, could translate into clinical benefit, due to the proximity of these regions.

Materials and methods

One hundred and twelve consecutive conformal radiotherapy plans were correlating the average dose to the IMC with the type of surgery employed, the extent of disease and the irradiation techniques.

Results

The mean doses to IMC after modified radical mastectomy (MRM), modified radical mastectomy with immediate reconstruction (MRM + R), and breast conservative surgery (BCS) were 30.34 Gy, 30.26 Gy, and 18.67 Gy, respectively. Significant differences were identified between patients who underwent MRM or MRM + R over BCS (p = 0.01 and 0.003, respectively), but not between MRM and MRM + R (p = 0.88). Mean doses to IMC were greater in patients with T3–T4 tumors when compared with more initial stages (≤T2) (p = 0.0096). The lymph node involvement also correlated with higher average doses to IMC (node positive: 26.1 Gy × node negative: 17.8 Gy, p = 0.0017).

Conclusions

The moderate dose level to the IMC in the unintentional irradiation scenario seems to be insufficient to treat the subclinical disease, although it could have an impact in patients undergoing mastectomy.     

Normoxic polymer gel dosimetry using less toxic monomer of N-isopropyl acrylamide and X-ray computed tomography for radiation therapy applications

Background

Polymer gel dosimetry has been used extensively in radiation therapy for its capability in depicting a three dimensional view of absorbed dose distribution. However, more studies are required to find less toxic and more efficient polymers for application in radiotherapy dosimetry.

Aim

The purpose of this work was to evaluate the N-isopropyl acrylamide (NIPAM) gel dosimetric characteristics and optimize the protocol for X-ray computed tomography (CT) imaging of gel dosimeters for radiation therapy application.

Material and methods

A polymer gel dosimeter based on NIPAM monomer was prepared and irradiated with ⁶⁰Co photons. The CT number changes following irradiation were extracted from CT images obtained with different sets of imaging parameters.

Results

The results showed the dose sensitivity of ΔN_CT (H) = 0.282 ± 0.018 (H Gy⁻¹) for NIPAM gel dosimeter. The optimized set of imaging exposure parameters was 120 kV_p and 200 mA with the 10 mm slice thickness. Results of the depth dose measurement with gel dosimeter showed a great discrepancy with the actual depth dose data.

Conclusion

According to the current study, NIPAM-based gel dosimetry with X-ray CT imaging needs more technical development and formulation refinement to be used for radiation therapy application.     

Measurement of body composition in response to a short period of overfeeding

Background

Obesity and overweight are increasing in prevalence in developed countries as a result of changing dietary habits and a lack of physical activity. The purpose of the present study was to evaluate the changes in body composition during short-term overfeeding using the three-component model, which is composed of fat mass (FM), total body water (TBW), and fat-free dry solids (FFDS).

Methods

Ten healthy men completed 3 days of overfeeding during which they consumed 1,500 kcal/day more energy than consumed in their normal diets. Body composition was evaluated at three time points: the day before and after their normal diets and the day after the 3-day overfeeding diet.

Results

Before and after their normal diets, there were no significant differences in body weight and composition, but after 3 days of overfeeding, body weight, TBW, and FFDS increased 0.7, 0.7, and 0.2 kg, respectively (P <0.0001). There was no significant difference in FM between the normal and overfeeding diets.

Conclusion

This study suggests that TBW gain contributes to weight gain following a short-term overfeeding.     

Is dose escalation achievable for esophageal carcinoma?

Aim

To investigate the feasibility of dose escalation using rapid arc (RA) and Helical Tomotherapy (HT) for patients with upper, middle and distal esophageal carcinomas, even for large tumor volumes.

Background

In esophageal cancer, for patients with exclusive radio-chemotherapy, local disease control remains poor. Planning study with dose escalation was done for two sophisticated modulated radiotherapy techniques: Rapid arc against Tomotherapy.

Materials and methods

Six patients treated with a RA simultaneous integrated boost (SIB) of 60 Gy were re-planned for RA and HT techniques with a SIB dose escalated to 70 Gy. Dose volume histogram statistics, conformity indices and homogeneity indices were analyzed. For a given set of normal tissue constraints, the capability of each treatment modality to increase the GTV dose to 70 Gy was investigated.

Results

Either HT or VMAT may be used to escalate the dose delivered in esophageal tumors while maintaining the spinal cord, lung and heart doses within tolerance. Adequate target coverage was achieved by both techniques. Typically, HT achieved better lung sparing and PTV coverage than did RA.

Conclusions

Dose escalation for esophageal cancer becomes clinically feasible with the use of RA and HT. This promising result could be explored in a carefully controlled clinical study which considered normal tissue complications and tumor control as endpoints.     

Effects of seat surface inclination on respiration and speech production in children with spastic cerebral palsy

Background

Respiratory and speech problems are commonly observed in children with cerebral palsy (CP). The purpose of this study was to identify if inclination of seat surface could influence respiratory ability and speech production in children with spastic diplegic CP.

Methods

Sixteen children with spastic diplegic CP, ages 6 to 12 years old, participated in this study. The subjects’ respiratory ability (forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), peak expiratory flow (PEF), and maximum phonation time (MPT)) were measured in three sitting conditions: a seat surface inclined 0°, anterior 15°, and posterior 15°.

Results

FVC was significantly different across three inclinations of seat surface, F(2, 45) = 3.81, P = 0.03. In particular, the subjects’ FVC at a seat surface inclined anterior 15° was significantly greater than at a seat surface inclined posterior 15° (P < 0.05). However, FEV1, PEF, and MPT were not significantly affected by seat surface inclination (P > 0.05).

Conclusions

The results suggest that anterior inclination of seat surface may provide a positive effect on respiratory function in children with spastic diplegic CP.     

Use of planar kV vs. CBCT in evaluation of setup errors in oesophagus carcinoma radiotherapy

Aim

The aim of this study is to evaluate differences in terms of the setup errors observed using kV planar image compared to CBCT for oesophageal cancer patients.

Background

Planar kV images are quick to acquire but only allow the observation of bony structures. CBCT allows the evaluation of soft tissues, which includes the oesophagus (and tumour) and OAR, giving a more accurate verification of the positioning.

Materials and Methods

All patients were imaged with both techniques between January 2012 and March 2014 were included in the study (16 patients, 212 kV images and 116 CBCT images). Differences between the setup errors observed on the two images modalities were studied. A correlation study between TNM staging, tumour location and immobilization systems with setup errors was also done. Finally, the calculation of systematic and random errors allowed to determine the CTV–PTV margin.

Results

A significant discrepancy (p < 0.05) between the setup errors observed with kV and CBCT was observed in the lateral direction. No statistical correlation was found between setup errors and tumour location, immobilization system or TNM staging. The CTV–PTV margin was smaller with CBCT in the vertical (0.6 cm vs. 0.9 cm) and longitudinal (0.7 cm vs. 1 cm) directions and smaller with kV for the lateral directions (0.8 cm vs. 0.9 cm).

Conclusions

The chosen modality influences the setup error observed which will influence the correction applied. Allowing a better observation of the volumes of interest, CBCT should be the modality of choice in this pathology. The CTV–PTV margins could be shrunk if CBCT is used.     

Detection of setup uncertainties with 3D surface registration system for conformal radiotherapy of breast cancer

Aim

To investigate the clinical application of a technique for patient set-up verification in breast cancer radiotherapy based on a 3D surface image registration system.

Background

Accurate and reproducible patient set-up is a prerequisite to correctly deliver fractionated radiotherapy. Various approaches are available to verify and correct patient setup for 3D image acquisition in a radiation treatment room.

Materials and methods

The study analyzed the setup reproducibility of 15 patients affected by breast cancer and candidates for conformal radiotherapy by using the AlignRT system (VisionRT, London, UK). At the initial setup, electronic portal imaging device (EPID) images were compared with Digitally Reconstructed Radiographs (DRRs) and a reference three-dimensional (3D) surface image was obtained by AlignRT. Surface images were acquired prior to every subsequent setup procedure. The systematic and random errors along longitudinal and vertical directions were measured and compared for the two systems.

Results

The procedure for surface registration, image acquisition and comparison with the reference image took less than 1 min on average. The T test for systematic error showed no significant difference between the 2 verification systems along the longitudinal (p = 0.69) and vertical (p = 0.67) axes. The T-test for random error showed a significant difference between the 2 systems along the vertical axis (p = 0.05).

Conclusion

AlignRT is fast, simple, non-invasive and seems to be reliable in detecting patient setup errors. Our results suggest that it could be used to assess the setup reproducibility for breast cancer patients.