A new study has reported mixed results concerning whether survival outcomes for pN0 breast cancer patients differ depending on whether they undergo sentinel node biopsy or more extensive axillary lymph node dissection. Stage pN0 refers to no regional lymph node metastasis (according to histology) and no additional examination for isolated tumor cells. Recent studies reporting that extensive axillary lymph node dissection in pN0 breast cancer patients may have a survival benefit compared to sentinel node biopsy have challenged the premise of sentinel node biopsy. The study used data from two large databases to calculate survival in relation to the extent of axillary lymph node dissection in pN0 breast cancer patients.

In the first analysis, which included 1,607 pN0 patients from a single institution, it was found that less extensive axillary lymph node dissection significantly increased the risks of distant recurrence and death from breast cancer, but not of locoregional recurrence (recurrence in the breast, chest wall, or lymph nodes). The second analysis used data from a nationwide Korean registry concerning 17,672 pN0 breast cancer patients. Patients in this database with more than 20 dissected lymph nodes were found to have significantly better overall survival and breast cancer-specific survival than those with either 10 to 20 or less than 10 dissected lymph nodes. However, those who underwent sentinel node biopsy alone had overall survival and breast cancer-specific survival comparable to those of patients who underwent extensive axillary lymph node dissection (more than 20 dissected lymph nodes), despite the much smaller number of lymph nodes removed. The authors conclude that extensive axillary lymph node dissection is associated with better survival and less systemic recurrence than less extensive axillary lymph node dissection in patients with pN0 breast cancer. However, they also note that sentinel node biopsy alone showed similar survival results as extensive axillary lymph node dissection, supporting the long-term oncologic safety of sentinel node biopsy.

Implications of the study results regarding lymph node dissection

Because of its contradictory results, this study has little in the way of practical implications for breast cancer patients. As a surgery, sentinel lymph node biopsy is far preferable to more extensive axillary lymph node dissection, which can cause considerable damage to the arm and is more likely to result in lymphedema. On the other hand, detection of micrometastases in lymph nodes has been found to be important and breast cancer patients want to maximize their chances of long-term survival.

It has not been established whether surgically removing lymph node micrometastases will prolong survival, although one recent study suggests it is not necessary. Sentinel node biopsy and axillary lymph node dissection are performed to help stage breast cancer and determine treatment. If positive lymph nodes are found, it usually means a woman will undergo chemotherapy, even if the primary tumor in the breast is small. Since lymph node metastases can have different receptor status from the primary tumor in the breast, the receptor status of any such metastasis should be determined in order to optimize treatment.