Screening for colorectal cancer.

In the United Kingdom there are almost 31,000 new cases of colorectal cancer each year and nearly 20,000 deaths. It is the second most common cause of all deaths from cancer in the United Kingdom. The efficacy of screening with faecal occult blood tests to detect and treat tumours at an early stage, and thereby to reduce mortality, is currently being assessed in several randomised controlled trials. In general, faecal occult blood tests have a low sensitivity and only moderate levels of uptake among the population invited for screening. Until the studies in Denmark, Sweden, and Nottingham report their findings, there is no case for providing such screening routinely to an asymptomatic population. Detecting and removing premalignant adenomas by flexible sigmoidoscopy could be more effective than detecting early localised, asymptomatic cancers in reducing deaths from colorectal cancer. It is estimated that screening people at about the age of 60 by a single flexible sigmoidoscopy examination with appropriate colonoscopic surveillance could prevent 5500 cases of colorectal cancer and 3500 deaths in the United Kingdom each year. A randomised controlled trial to confirm these observations should be seen as a priority.     

Screening for breast cancer.

The feasibility of mass population screening for breast cancer by clinical examination and x-ray mammography was studied. The results indicate that such a programme could be conducted effectively by non-medical staff and be safe from the dangers of irradiation. The response rate of women invited for screening suggests that such a service is acceptable to the general public. The additional work load produced by screening would not overburden the existing surgical services.     

Screening for lung cancer.

The survival from bronchogenic carcinoma is highly dependent upon stage at the time of treatment. This is particularly true for squamous cell carcinoma, adenocarcinoma, and large cell carcinoma, but holds true for small cell carcinoma as well. The problem presented to the medical profession has been to find a practical means of detecting lung cancer while it is still at an early stage. Three studies in progress have indicated that a larger proportion of the patients may be found to have early stage lung cancer when screened with a combination of chest X-rays and sputum cytology. However, the detection of these early stage cases has not yet been translated into an improvement in the overall mortality rate from lung cancer.     

Screening for occult lung cancer.

A pilot screening program for the early detection of lung cancer was carried out in Saskatchewan in 1968 using chest roentgenography and cytologic examination of sputum samples. The yield from 23 000 men aged 40 years and over was only 10 cases. Nine of the men had advanced disease. One had occult lung cancer. A period of 31 months elapsed between the discovery of malignant cells in this patient''s sputum and roentgenographic localization of the tumour. Following pneumonectomy he has survived with no discernible residual or metastatic tumour for 12 years. The morphologic changes in the resected lung provided a basis for discussing the preclinical phase of squamous cancer of the lung, the treatment of occult cancer and multicentric primary pulmonary tumours. The survey would have been more successful with a narrower target group and more frequent examination.     

Screening for breast cancer. Report from Edinburgh Breast Screening Clinic.

As part of a trial to determine the feasibility of screening for breast cancer, 3952 women aged 40--59 years were screened once or more over two years. They represented 82% of those invited by a personal letter from their GPs. Each woman underwent mammography, two clinical examinations, and, usually, thermography. Further investigations included needle aspiration of cysts, xeromammography, and biopsy. Of the 125 women who underwent biopsy, 18 proved to have cancer. Because of the high response rate and consequent large sample of normal women the biopsy and cancer detection rates were low. Clinical examination and mammography together were more effective in detecting significant lesions than either procedure alone, and knowledge of the mammographic findings enabled the examiner to detect more abnormalities. Screening was expensive: each cancer detected cost about 6000 pounds, excluding data processing, surgical, and pathological costs. The clinic has now adopted a more simplified screening regimen, which should reduce costs, but more accurate imaging techniques and ways of identifying high-risk cases are needed.     

Screening for cervical cancer by direct inspection.

OBJECTIVE--To assess the efficacy of visual screening for cervical cancer in the maternal and child health setting. DESIGN--Clinical and cytological screening. SETTING--Maternal and child health centres, Delhi. SUBJECTS--44,970 women attending the centres from May 1988 to March 1991. RESULTS--238 cancers in early stages (0-IIa) were detected cytologically and proved through biopsy. Prevalence of cancer in women defined as high risk through examination by speculum was 29/1000 as compared to 1.53/1000 among women with a normal looking cervix. Though only 11.4% women belonged to the high risk category, 63% had early stage cancer. If all women with bleeding symptoms were included in the high risk category, the yield of cancer would be 71.4% (170/238) by referring only 15.6% of women attending maternal and child health centres for further evaluation through cytology or colposcopy. CONCLUSION--Though visual screening is a suboptimal strategy in comparison to the cytological screening, it may be useful where there is a heavy load of prevalent cancer and where cytological screening may not be available for years to come.     

Screening and self examination for breast cancer.

Breast cancer is the major form of cancer in women, with nearly 30,000 new cases and over 15,000 deaths in the United Kingdom each year. Breast screening by mammography has been shown in randomised trials to reduce mortality from breast cancer in women aged 50 and over. An NHS breast screening programme has been in operation in the United Kingdom since 1988. Its aim is to reduce mortality from breast cancer by 25% in the population of women invited to be screened. The uptake of mammography among the eligible population may be the single most important determinant if the programme is to be effective. Primary care teams have an important part to play in encouraging women to attend for screening and in providing information, advice, and reassurance at all stages of the screening process. To date, routine breast self examination has not been shown to be an effective method of screening for breast cancer and should not therefore be promoted as a primary screening procedure. There is, however, a case to be made for women to become more "breast aware."