After a breast cancer operation, the removed tumor is always examined, as its subtype can provide an indication of how aggressive the disease is. The patient’s lymph nodes are not analyzed as fully. Yet, the breast tumor can sometimes appear to be of a less aggressive type while the subtype in the lymph nodes gives a different and more worrying picture.

In these cases, it is the lymph nodes that provide the correct prognosis, according to new research at Lund University in Sweden. An analysis of the proliferation, hormone receptor status, and HER2 status of the lymph nodes would in many cases show a significantly more accurate picture of the risk for metastases, meaning a recurrence and spread of the disease to other organs.

“It would be easy to add such an analysis. It does not require any expensive specialist technology, but only an extension of the normal, routine pathology work,” said lead author Lisa Rydén, MD, a consultant surgeon and researcher at Lund University in Sweden. The study was published in Breast Cancer Research and Treatment (2013; 140(1):93-104).

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The study covers 500 women in the early stages of breast cancer who underwent surgery in Lund or Helsingborg. Early-stage breast cancer is when the cancer has not yet spread to other organs. However, in approximately one third of all the women who underwent surgery for early-stage breast cancer, there were traces of the tumor in the lymph nodes, which can provide important additional information.

“Sometimes the molecular study showed the same subtype in the breast tissue and in the lymph nodes. But sometimes the types were different. And when we investigated the outcomes for the women 10 years later, the prognosis followed the subtype that was present in the lymph nodes and not the one in the breast,” said Rydén.

Thus, when doctors only examine the breast tissue, there is a risk that the tumor will be found to be of a low-risk type, which affects decisions on further treatment. Meanwhile, the lymph nodes may show signs of a more aggressive form of tumor that is never discovered.

“If, on the other hand, we start routinely analyzing the lymph nodes as well, we can treat women in such cases with additional cytostatic and targeted drugs after their operation. This could prevent later recurrence of the disease,” stated Rydén.

A fairly small proportion of the patients in the study showed a difference in tumor type between the breast tissue and the lymph nodes. But since breast cancer is such a common disease, the number of patients affected nationally and globally will still be considerable and, for them, the difference can be that between life and death, Rydén pointed out.