Early-stage breast cancer: Microscopic tumor spread is no worry

Women with early-stage breast cancer have plenty of procedures and treatments to deal with. So it may come as welcome news that a large clinical trial has found no reason for doctors to perform two tests that were thought to help predict patient survival. Writing in the Journal of the American Medical Assn., the researchers say that the test results are meaningless.

The tests in question involve looking for micrometastasis – microscopic evidence of a breast tumor’s spread – in sentinel lymph nodes and in bone marrow. Some earlier studies had found that women with those micrometastases were more likely to see their cancers recur and/or die of breast cancer sooner. But those studies were retrospective – not the forward-looking studies that researchers prefer. They also involved women with more advanced cases of breast cancer, and some of the studies were so old that they didn’t take into account advances in treatment.

So the American College of Surgeons Oncology Group began this trial in 1999. They recruited 5,119 women from around the country with early-stage breast cancer whose sentinel lymph nodes were examined. In addition, 3,413 of the women had bone marrow biopsies.

The researchers, led by Dr. Armando Guiliano of Cedars-Sinai Medical Center in Los Angeles, found evidence of micrometastasis in 10.5% of the women whose lymph nodes were tested and in 3% of the women whose bone marrow was analyzed. But in both cases, women with microscropic spread of their tumors fared just as well as women without such spread.

The research team reported that 95.1% of women with micrometastases in their lymph nodes were still alive five years later, compared with 95.7% of women without – a difference that was statistically insignificant. In addition, 90.4% of the former group remained disease-free after five years, compared with 92.2% in the latter group.

When researchers took into consideration the age of the patients and the size of their primary tumors, the presence of micrometastases in bone marrow had no correlation with the odds that their cancer would return or that it would kill them.

In their study, the researchers noted that the College of American Pathologists doesn’t recommend checking sentinel lymph nodes for micrometastasis, though many laboratories do so anyway.

A summary of the study is available on the JAMA website.