• Higher levels of mammographic breast density, expressed as a percentage of total breast area or volume, may be a better predictor of breast cancer risk than any other established breast cancer risk factors. Breast density is a measure of the relative proportion of fat, connective tissue, and glandular epithelial tissue in the breast.

• Women with breast cysts of type I, that is, cyst fluid with a high ratio of potassium:sodium, have an increased risk of breast cancer compared to those with type II cysts (fluid with low potassium:sodium ratio). This ion ratio could be used as a marker to identify high risk women.

• Long-term follow-up study shows that prophylactic mastectomy may reduce risk of breast cancer in high-risk individuals. Another study reveals that a large proportion of women who were provided with genetic counseling considered removal of both ovaries.

• The National Human Genome Research Institute, through studies conducted by a special task force, has developed recommendations for cancer surveillance and risk reduction for individuals carrying mutations in the BRCA1 and BRCA2 genes, the newly discovered genes conferring inherited predisposition to breast and ovarian cancer.

• Color Doppler Sonography performed with a transvaginal probe affords detection of tumor neovascularity as a means to distinguish benign (physiologic) from malignant ovarian masses.. This overview will describe and illustrate the application and limitations of this technique in evaluating women with no risk factors or those with known risk factors.

• Tumor growth is supported by new blood vessel formation (angiogenesis) that meets nutritional requirement of the growing tumor. In laboratory and animal models antiangiogenic agents are found to exert inhibitory effect on breast and prostate cancer growth.

• A new gene, called Hs-cul-4A identified two years ago, is found to be overexpressed in breast cancer cells compared to the same gene in normal breast tissue. Protein produced by this gene is thought to be involved in the control of cell cycle, which regulates cell growth. Another study shows that individual with mutations in BRCA1 and BRCA2 -- the so-called "breast cancer genes" -- are more likely to have an accumulation of abnormalities in other segments of their genetic code.

• The aging population, improved detection methods and perhaps unknown factors contribute to a continuous increase of prostate cancer incidence. The verdict as to the significance of early diagnosis and intervention in the improvement of survival is still out. However, recent efficient combination treatments with a cocktail of endocrine blockers, causing pharmacological castration, underline the need for reliable laboratory markers which allow the monitoring of success (or failure) of therapy. The most prominent and widely used is the Prostate Specific Antigen (PSA); a review of recent observations indicates that the term "specific" is incorrect and that PSA is present in a variety of malignant tumors and even normal tissues.

• Genetic abnormalities can be employed as markers to distinguish chemotherapy resistant infants with inoperable or metastatic neuroblastoma and innovative treatments can be designed for them.

• Neuroblastoma, a type of nervous system tumor, has many characteristics indicating that early detection might improve outcome. However, most of the tumors regress spontaneously. Therefore screening for this tumor shows increase in incidence without decreasing the incidence of unfavorable advanced-stage disease that is fatal.

• Introduction of inducible gene from nitric oxide synthase, the enzyme that produces nitric oxide in tumor cells generates high levels of nitric oxide and kills not only the altered cells but also nearby unaltered tumor cells. The finding suggests that this form of gene therapy does not require genetic alteration of every cell in a tumor to be effective.

• Endogenous and exogenous protease inhibitors are numerous and ubiquitous. They have been associated with reduced cancer incidence by epidemiologists and there are now many experimental studies which support their anticarcinogenic effect. Since there are so many and very different protease inhibitors, their action is multifaceted and certainly not direct – which allows for attractive working hypotheses, none of which has been proven so far. Nevertheless, there is good evidence for several sites of action, both in vitro and in vivo, which merits attention and support.

• A Bcl-2 gene related protein, BAX, the expression of which is dependent on p53 activity is found to be involved in p53-dependent apoptosis in an animal brain tumor model. This is the first indication in vivo that a p53-regulated gene is participating in p53-dependent apoptosis.

Glossary

• A glossary of unfamiliar words and jargons in Cancer Watch, April 1997.