Patients with microinvasive breast cancer (Tmic) may only experience minimal benefits from routine node sampling and support management, according to a study published in TheBreast Journal.
Tmic is managed similarly to invasive tumors — typically with surgical treatment such as lymph node sampling — even though the pathologic behavior and prognosis of Tmic may be more similar to noninvasive cancers.
For this retrospective study, researchers assessed the cases of 294 eligible patients with Tmic between 2001 and 2015. Investigators reviewed available pathologic and clinical data, such as microinvasive carcinoma histology, hormone receptor/HER2 status, lymphovascular invasion, number of microscopic invasive foci, associated in situ tumor size and grade, margin status, and recurrence and survival outcomes. The mean follow-up was 4.6 years.
Of the 260 patients with Tmic who underwent axillary staging, only 4 (1.5%) patients had lymph node metastases. All Tmic cases with lymph node metastases were associated with relatively large ductal carcinoma in situ (DCIS) tumors (>5 cm); the median DCIS tumor size for the study was 2.5 cm. There were no instances of lymph node metastases with microinvasive lobular carcinoma.
During the follow-up period, no cases of regional or distant recurrence/metastases or cancer-related deaths were reported.
Results show that the pathologic behavior of Tmic is similar to noninvasive breast cancers, particularly for patients with microinvasive lobular carcinoma or DCIS-associated microinvasive ductal carcinoma smaller than 5 cm.
The authors concluded that “these data have important implications in the modern era of breast cancer imaging and treatment where early‐stage disease is being detected at increasing rates. Tailoring treatment to maximize oncologic outcomes while minimizing potentially unnecessary interventions has important implications for patient satisfaction and systemic resource utilization.”
Lillemoe TJ, Tsai ML, Swenson KK, et al. Clincopathologic analysis of large series of microinvasive cancers[published online February 24, 2018]. Breast J. doi: 10.1111/tbj.13001