David Thomas

Screening for colorectal cancer: what are the costs?

We examined a screening program for colorectal cancer in South Australia in terms of its overall direct costs to society and costs to participants. The best estimate of the cost per cancer detected was

Experiences in providing a screening service for colorectal cancer from a pathology laboratory

18,924 (Australian dollars). Potential improvements in health outcome through screening are discussed in light of these costs.

Lactate dehydrogenase—another tumour product?

Aim To provide a colorectal cancer screening service for the general public, based on the detection of blood in faeces, that was effective, affordable and convenient. Methods Kits for collecting faecal specimens were sold directly to the public and, after collecting three specimens, kits were transported to the laboratory for testing by an immunochemical procedure involving a positive cut‐off value. Reports were sent to participants and their nominated doctors who were requested to provide information on participants testing positive. Results Over a 10‐year period, 35 139 kits were analysed and 5.63% were positive. After follow‐up, 7.4% of positive testing participants were found to have colorectal cancer, 23.4% adenomas, 34.6% miscellaneous non‐neoplastic pathology and in 25.0% no abnormality was found. Sixty‐six per cent of cancers were early stage, Dukes stages A and B. There were 35 139 kits processed on 16 240 individuals, indicating that a number were repeat testing. Conclusions The screening service was able to detect a high yield of colorectal pathology, especially early stage neoplasia which is curable, and encouraged repeat testing. Education of doctors about how to investigate a positive test, and of participants about symptoms, have been important lessons arising from this screening service.

EVALUATION OF AN IMMUNOLOGICAL TEST FOR OCCULT BLEEDING FROM COLORECTAL NEOPLASIA

Sporadic reports have appeared of increased lactate dehydrogenase activity (LD) and/or abnormal lactate dehydrogenase isoenzymes associated with malignant tumours. A recent report has shown a positive association of LD with tumour mass in a number of patients with advanced testicular tumours. To explore this association further, we have studied 5 patients with a variety of tumours, in all of whom isolated increases in LD were observed. Determinations of total serum LD have been made at the onset and throughout courses of chemotherapy. Isoenzyme fractionations have been made on several occasions using heal stability and electrophoretic techniques. In one case similar studies have been performed on homogenates of hepatic metastatic deposits. In all patients increases in LD were predominantly of LD1 and LD2 iso-enzymes. Tumour diagnoses were 2 definite and 1 probable testicular teratoma, one undifferentiated carcinoma arising from floor of mouth, and one malignant melanoma. Reductions in LD were observed during chemotherapy, and these coincided with resolution of tumour mass in each patient. In 2 patients whose tumours escaped control increases in tumour mass were associated with rises in LD. Tissue studies on an hepatic metastasis in a patient with definite testicular teratoma showed large amounts of LD1 and LD2. In the patient with probable testicular teratoma an additional abnormal LD isoenzyme was observed between LD2 and LD3 iso-enzymes when using electrophoretic separation. Since LD1 is almost exclusively cardiac in origin, and none of these patients had overt cardiac disease, it is proposed that LD is being produced by and released from these tumours. Although not a common phenomenon. there may be some clinical usefulness in examining LD as a tumour marker, as it is easily and frequently measured.