Is the removal of lymph nodes always necessary in ductal carcinoma in situ?

The authors aimed to evaluate the point at which the removal of a node in patients with breast cancer was necessary.

Sentinel lymph nodes (SLN) are first nodes (small bean-shaped organs located close to blood vessels) to which cancer can spread. Cancer-positive SLN’s have become increasingly prevalent in ductal carcinoma in situ breast cancer (DCIS; an early stage of breast cancer in which the cancer cells are confined to the milk ducts of the breast).

An SLN dissection (removal of the affected lymph node) is often promoted to patients with affected lymph nodes; however, studies show that this may be over-treatment for those with DCIS.

The aim of this study was to determine the effect that cancer-positive lymph nodes have on the prognosis of patients with breast cancer; specifically those with DCIS.

A total of 1,234 patients with breast cancer underwent SLN dissection, of whom 77% had previously received a mastectomy (removal of the entire breast). 74% patients had estrogen receptor positive breast cancer (ER+; specific proteins present on the surface of cancer cells) and 56% had progesterone receptor positive breast cancer (PR+; specific proteins present on the surgace of cancer cells).

Positive SLN’s were identified in 11% of the patients. Of the subgroup of 259 patients with invasive cancer (the cancer has the ability to spread), 25% had positive SLN findings. For those with pure DCIS, 5-year survival rates were almost 100% regardless of whether SLN's were positive or negative. 

Positive SLN findings appeared to have an impact on prognosis only in the presence of occult invasion (cancer affects the lymph nodes but cannot be found in the breast tissue). Patients with a positive SLN with occult invasion had a 5 year survival-rate of 91.7%.

The authors suggested that, except for patients at high risk of invasive disease, routine SLN dissection for DCIS is not warranted. 

This study took place at one institution, and so should be repeated at further institutions to ensure that the results are valid.