Abstract
Dear Editor,
The correct adjuvant management of internal mammary nodes (IMNs) in breast cancer treatment is still unclear (1), so further studies would be useful. We read with interest the report by Lukesova et al (2), a retrospective study on predictive risk factors for IMN drainage in patients with breast cancer. In their study, a series of patients undergoing sentinel node biopsy because of surgical treatment for breast cancer was reviewed and several factors including tumor size, patient age, tumor location, estrogen and progesterone receptor expression, HER2 status, axillary node status, Ki-67 expression and histology were analyzed as possible risk factors for drainage into IMNs.
We believe, however, that some clarification is needed. The sentinel node biopsy procedure allows to show the physiological lymphatic pathway through the migration of radiocolloid tracer injected into the primary tumor site in order to guide sentinel lymph node biopsy for histological assessment. Radiocolloid detection does not indicate the presence of nodal metastasis.
Even if some known tumor factors are related to a worse prognosis and IMN metastasis, such as age under 35 years (3), high tumor grade and lymphovascular invasion (3), or the presence of metastasis in axillary nodes (4, 5), they may not affect the lymphoscintigraphy result because the physiological lymphatic pathway can in no way be modified by biological disease features. This means that, in our opinion, patient age, estrogen and progesterone receptor expression, HER2 status, axillary node status, Ki-67 expression and histology have been incorrectly evaluated as possible risk factors for IMN drainage by Lukesova et al (2).
Six risk factors, including age <50 years, tumor location in central and inner quadrants, larger tumor size, positive HER2 status, progesterone receptor expression, and axillary lymph node involvement were found to be statistically related to radiocolloid flow into IMNs using the chi-square test with Bonferroni correction. This statistical analysis is questionable because a multivariate analysis would be recommended.
The study's conclusion that “the combination of 1 or more risk factors with lymph node drainage into IMNs could potentially identify patients who would benefit from IMN radiotherapy or surgical IMN sampling” is questionable as, at the moment, the presence of radiocolloid detection in IMNs cannot be directly related to the risk of IMN metastases; this study defines predictive risk factors for IMN drainage in patients with breast cancer, not for IMN metastases, which means that these factors might even be related to a lower risk of metastases.
Even if this study is limited by its retrospective nature, it would be interesting to know the outcome of those patients showing drainage into IMNs. Further studies are recommended to define the correct management of IMNs.
Footnotes
Financial support: None.
Conflict of interest: None.