NEW YORK (Reuters Health) - A variety of factors, including the number of involved and uninvolved lymph nodes, may be predictive of risk of locoregional failure following mastectomy for breast cancer, and such patients might benefit from radiotherapy (RT), according to researchers.

"Postmastectomy RT is generally recommended in most guidelines if 4 or more nodes are involved," lead investigator Dr. Per Karlsson told Reuters Health. "RT in the 1-to-3 positive-node group is controversial."

In the May 20th issue of the Journal of Clinical Oncology, Dr. Karlsson of the University of Gothenburg, Sweden and colleagues note that they studied data on 6600 patients treated with chemotherapy and endocrine therapy and followed for a median of 14 years. All had had mastectomy without RT.

In the 2588 node-negative patients, there was no group with a 10-year locoregional failure risk exceeding 20%. Thus, say the investigators, there was no indication of worse prognosis based on few uninvolved nodes in node-negative disease identified through sentinel node biopsy, or through selective node sampling based on a few palpable nodes.

However, in the 4072 node-positive patients, even after adjustment, increasing numbers of uninvolved nodes were associated with decreased risk of locoregional failure.

Compared to those with the lowest number of uninvolved nodes, premenopausal women with the highest number had a 35% decreased risk of locoregional failure. For postmenopausal women, the corresponding risk was reduced by 46%.

The 10-year cumulative incidence of locoregional failure was 20% in patients with 1 to 3 involved lymph nodes and fewer than 10 uninvolved nodes. Being less than 40 years of age and vessel invasion were associated significantly with increased risk.

"Our results indicate that patients with 1 to 3 positive nodes and a low number of identified uninvolved nodes, vascular invasion or young age have a high rate of locoregional failure postmastectomy," concluded Dr. Karlsson, "and they should be considered for similar treatment as patients with 4 or more nodes."

--David Douglas

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