Close monitoring advised; Study: breast ca tied to malignant melanoma risk; Most women studied received breast cancer diagnosis first, melanoma dx within 1 year.(News)

NEW ORLEANS -- Women who are diagnosed with breast cancer appear to have an increased risk of malignant melanoma, particularly during the first year following diagnosis of the breast tumor, reported Dr. Rony Weitzen at the annual meeting of the American Society of Clinical Oncology.

Dr. Weitzen and colleagues at the Institute of Oncology. Sheba Medical Center, Tel Hashomer. Israel, analyzed incidence data from Israeli tumor registries, and found a nearly twofold overall increase in primary malignant melanomas in women with breast cancer. There was no overall increase in breast cancer incidence among women diagnosed with primary melanomas.

"A woman with breast cancer should be considered to be at high risk for melanoma, and should be monitored very closely," Dr. Weitzen told this newspaper. He presented the findings as a poster at the ASCO conference.

This is not the first report of a possible link between breast cancer and melanoma, but it is by far the largest and most rigorous. Past reports have come to conflicting conclusions. Dr. Weitzen said his team began to take the possible link more seriously when they had four cases of double primaries (breast cancer and melanoma) in a period of a couple of months. "This raised our attention to the risk of both tumors in women, prompting us to study the registries," he explained.

Using Israeli cancer registry data from 1960 to 2000, they counted melanoma diagnoses among 51,000 female breast cancer patients, and breast cancer diagnoses among 6,248 melanoma patients. Dr. Weitzen noted that Israel has a similar prevalence of breast cancer in the general population as does the United States.

There were a total of 276 malignant melanomas among the women with breast cancer, which was considerably higher than the 157 expected based on prevalence figures for the general Israeli population. The standardized incidence ratio (SIR). essentially a measure of relative risk, was 1.76. Most of the women had their melanomas diagnosed within the first year following the primary breast cancer diagnosis, and the SIR during that first year was 2.28.

Overall, there were 267 breast cancers in the 6,248 women with primary melanoma, and this is consistent with the breast cancer prevalence in the general Israeli population. The SIR for breast cancer in women with melanoma was 1.03. However, during the first year after a melanoma diagnosis, the SIR was quite a bit higher. There were 44 breast cancer cases diagnosed within 12 months of the melanoma diagnoses, compared with 20 expected, giving an SIR of 2.21.