In the current study, Cody's team took four sections per node, analyzing two each for cell shape (morphology) and the presence of a molecular marker of cancer. Nine percent of patients were found to be node-positive using morphological criteria alone; the other 14 percent were detected using molecular markers. In both cases, survival was poorer than in patients who remained node-negative.
"What we are suggesting is that perhaps the staging system for lymph node metastases should be reevaluated in the next edition of the AJCC [American Joint Committee on Cancer] staging," he said.
Many sites already analyze more than one slice per node, he added. Sener's facility, for instance, uses 10.
According to Sener, the current findings underscore the need for additional systemic therapy, such as chemotherapy, in patients with SLN micrometastases. But he also noted that SLN micrometastases do not necessarily require surgical excision, as most patients with positive lymph nodes do not develop cancer under the arm.
Sener hypothesized that could be because each metastasizing cancer cell has a sort of molecular ZIP code, which governs where it can go. Under this hypothesis, the decreased survivability associated with micrometastases has less to do with the lymph nodes per se, than with what those positive nodes say about metastases elsewhere in the body.
"It may be that the presence of micrometastases in these lymph nodes may be a bystander phenomenon," Sener said, "a surrogate marker for the presence of the lung or liver ZIP code in these cells."
Cody noted one "significant caveat" to this study: Because breast cancer survival and treatment regimens have changed so dramatically over the past 30 years, this study says nothing about the prognostic implication of micrometastases discovered today. That will require prospective studies, several of which are ongoing.
Nevertheless, he said, "because we don't kn
All rights reserved