The clinical significance of minimal breast cancer: a pathologist's viewpoint.

We can draw the following conclusions about minimal breast cancer: The concept of minimal breast cancer as a stage of cancer that is 95% curable is a valid one, if minimal breast cancer is defined by strict parameters. Both 0.5 and 1.0 cm have been defined as the upper limit of size for minimal invasive cancer. Some data indicate that 0.5 cm is the preferable dividing line and that 1-cm cancers are no longer minimal. Other data suggest that the most important factor is axillary lymph node status. One-centimeter cancers are probably 95% curable if axillary lymph nodes are negative. Cancers of 0.5 cm and smaller in size are probably not 95% curable if axillary lymph nodes are involved. Carcinoma in situ appears to be highly curable, even if axillary lymph nodes are involved. Minimal breast cancer should include lobular carcinoma in situ (lobular neoplasia) and ductal carcinoma in situ regardless of nodal status, and (tentatively) invasive carcinoma smaller than 1 cm in total diameter, if axillary lymph nodes are not involved. Many cases of minimal breast cancer are asymptomatic. If special screening is not used, less than 10% of women with breast cancer will be at the minimal stage when diagnosed. Screening programs can increase this ratio to as much as one third of patients, perhaps even more. While serious questions about cost effectiveness of mass screening remain, screening programs appear to represent the best way of detecting minimal breast cancer. Screening programs should include careful history and physical examination, of course. The role of mammography is still controversial. It is probable that at least 50% of all minimal cancers would be missed without mammography. After a period of significant worry about the risk of radiation, opinion seems to be changing now and many authors are willing to accept the fact that mammography is of more benefit than risk for younger women. The HIP study would indicate that the risk/benefit ratio becomes favorable at age 50. Many authorities would now comfortably include mammography in the screening of women age 40 or older. Some authors believe that the benefits of mammography outweight the risks for patients of all ages. This question needs to be tested, and several randomized prospective clinical trials now in progress are doing just that. The legitimate worry over the risks of mammography should not obscure a very important fact.(ABSTRACT TRUNCATED AT 400 WORDS)