text_1: Allina study shows patients with very small breast tumors may forgo lymph node biopsies
text_2: The news release highlights a study — that joins about a dozen similar such studies over the past decade — trying to determine if looking for cancer spread in axillary (armpit) lymph nodes is worthwhile in a specific subtype of breast cancer called “microinvasive,” or “Tmic” (which refers to a tumor 1 millimeter or smaller). It remains a controversial surgical dilemma, in part, because some studies have found evidence of microinvasive cancer spreading to the lymph nodes 12.5% of the time, while this study, in particular, found the lowest incidence — just 1.5%. The authors conclude that, based on their findings, they believe microinvasive cancer is akin to ductal carcinoma in situ (DCIS) in that spread to the lymph nodes is rare. The researchers conclude from the study that routine node sampling in microinvasive cancer is of questionable benefit. The news release is very succinct in describing the findings of this small (under 300 patients) single-center study. Readers need more information before they can fairly weigh the researchers’ recommendation. For example, the release only notes that spread to the lymph nodes was found in patients with “relatively large” examples of DCIS, without clarifying what “fairly large” means; doesn’t note the average followup period for study participants, or what the outcomes were at the end of the study such as breast cancer recurrence, distant metastatic disease, or death from breast cancer. The release also does not mention if other tumor factors, such as hormone receptor status, were associated with spread to the lymph nodes. Recent advances in mammography and an increase in screening mean more breast abnormalities are detected; however, whether they should be labeled or treated as cancer is not always clear. Removal of some of the underarm lymph nodes (sentinel node biopsy) is generally performed at the time of surgery for early stage breast cancer in order to confirm whether or not there has been spread, and to inform treatment decisions. It is often not performed at the time of breast conserving lumpectomy in cases of DCIS; however, the decision whether to not to perform sentinel node biopsy in cases of microinvasive breast cancer is controversial. Breast cancer is staged according to tumor size (denoted as “T”) and lymph node spread (denoted as “N”). The “T” category ranges from 0-4 based on the size of the tumor in the breast. Tis represents ductal carcinoma in-situ, and T1 tumors are invasive breast cancers smaller than 2cm. Tmic is the designation used for microinvasive cancers — where the invasive component is less than 1mm. Future research in this area will help clarify whether Tmic should be approached more like DCIS or like an invasive cancer. Less treatment would have huge implications for surgeons, health care costs, and especially the quality of life for many patients.