Salvage cryosurgery of the prostate after radiation failure

Radiation therapy is one option for patients with localized prostate cancer. Despite advances in delivering radiation to the prostate gland with therapies such as brachytherapy and/or external beam radiation therapy, urologists will be faced with managing patients with rising prostate-specific antigen values and with positive biopsy results secondary to radiation-recurrent prostate cancer. If the cancer is detected early, salvage therapy can be initiated. Since salvage prostatectomy is associated with significant morbidity, patients are often left with the option of either watchful waiting or temporary palliation with hormone deprivation therapy, with its attendant toxicity. The introduction of third-generation cryotechnology using 17-gauge CryoNeedlestrade mark (Oncura, Inc., Plymouth Meeting, PA) and the recent modifications in the technique of salvage cryosurgery have enabled cryosurgeons to eradicate these tumors safely and with significantly decreased morbidity. Selection and management of patients, as well as the contemporary results of salvage cryosurgery, are discussed in this article.     

Biphasic effect of cryosurgery of the prostate on lymphocyte proliferation

In a preliminary study, cryosurgery of the prostate in patients with prostatic cancer has been observed to possess a biphasic effect on the proliferative responsiveness of peripheral blood lymphocytes (PBL) to the plant mitogen, phytohaemagglutinin. Phytohaemagglutinin-stimulated PBL cultured in autologous serum obtained up to 1 week postoperatively showed reduction from their preoperative levels. In contrast, cultures in homologous serum showed increased responsiveness following cryosurgery. Although depression of lymphocyte proliferation in autologous serum was transitory, gradually returning to approximate or exceeding levels of lymphocytic reactivity observed preoperatively, such depression may facilitate reduced host surveillance to potential infectious agents and to metastatic tumour cells, leading to an alteration of tumour-host homeostasis. Further studies will be required to delineate the possible clinical significance of the present observations.     

Numerical simulation for heat transfer in prostate cancer cryosurgery

A comprehensive computational framework to simulate heat transfer during the freezing process in prostate cancer cryosurgery is presented. Tissues are treated as nonideal materials wherein phase transition occurs over a temperature range, thermophysical properties are temperature dependent and heating due to blood flow and metabolism are included. Boundary conditions were determined at the surfaces of the commercially available cryoprobes and urethral warmer by experimental study of temperature combined with a mathematical optimization process. For simulations, a suitable computational geometry was designed based on MRI imaging data of a real prostate. An enthalpy formulation-based numerical solution was performed for a prescribed surgical protocol to mimic a clinical freezing process. This computational framework allows for the individual planning of cryosurgical procedures and objective assessment of the effectiveness of prostate cryosurgery.     

Effect of cryosurgery of the prostate in serum gonadotropin levels in prostatic cancer

Pituitary gland response to releasing hormone using the LH-RH loading test before and 4 weeks after cryosurgery of the prostate was investigated in eight patients with advanced prostatic carcinoma.In pre- and postoperative comparisons of all patients, there were no significant differences detected before and after surgery. But pituitary response to the releasing hormone was compared before and after the surgery in each of the patients; in one, depression and facilitation of FSH and LH secretion, respectively, were observed and there was a variation in the response of gonadotropin in each patient.Although the number of observable patients is still too low to draw any definite conclusions from the test results, one possible interpretation is that cryosurgery of the prostate may influence hormonal secretion from the pituitary gland.     

Computerized planning of prostate cryosurgery using variable cryoprobe insertion depth

The current study presents a computerized planning scheme for prostate cryosurgery using a variable insertion depth strategy. This study is a part of an ongoing effort to develop computerized tools for cryosurgery. Based on typical clinical practices, previous automated planning schemes have required that all cryoprobes be aligned at a single insertion depth. The current study investigates the benefit of removing this constraint, in comparison with results based on uniform insertion depth planning as well as the so-called “pullback procedure”. Planning is based on the so-called “bubble-packing method”, and its quality is evaluated with bioheat transfer simulations. This study is based on five 3D prostate models, reconstructed from ultrasound imaging, and cryoprobe active length in the range of 15-35 mm. The variable insertion depth technique is found to consistently provide superior results when compared to the other placement methods. Furthermore, it is shown that both the optimal active length and the optimal number of cryoprobes vary among prostate models, based on the size and shape of the target region. Due to its low computational cost, the new scheme can be used to determine the optimal cryoprobe layout for a given prostate model in real time.     

Vasectomy reversal in Nepal

Data from 157 men in Nepal who had vasectomy reversal are analysed. Most sought reversal within 5 years of vasectomy. Half of the men sought reversal because of the death of a male child, and about one-fourth because of the loss of a female child. Re-marriage was the primary reason for only 10% of the men. Those having reversal because of the loss of a male child were generally younger, and for almost half of this group, the age of their last child at the time of their vasectomy was under 2 years. The results suggest that the demand for reversal could be considerably reduced by more careful screening of the potential vasectomy acceptors.