Effectiveness of PET/CT and VATS for detecting and treating internal mammary lymph node metastasis: a case series.

Objective: We occasionally observed internal mammary lymph node metastases of breast cancer in a clinical setting. However, unlike a standard treatment in axillary metastasis, surgical resection for internal mammary lymph node metastasis is not prevalent because of unclear safety and benefits. Thus, we aimed to evaluate the diagnostic ability and clinical outcomes of positron emission tomography/computed tomography and video-assisted thoracoscopic surgery.

Methods: We retrospectively investigated 34 patients with breast cancer with abnormal 18F-fluorodeoxyglucose uptake in internal mammary lymph nodes, at a single centre, between January 2015 and June 2022 and identified 11 female patients (mean age ± SD, 51.5 ± 12.9 years) who underwent video-assisted thoracoscopic surgery resection. Positron emission tomography/computed tomography was used to determine the clinical stage. We reviewed the surgical pathology of eleven and two patients who underwent direct-view internal mammary lymph node resection to calculate the positive predictive value of positron emission tomography/computed tomography.

Results: Ipsilateral fluorodeoxyglucose accumulation was observed, with an average maximum standardized uptake value of 8.9 (range, 3.1-24.0). No perioperative complications occurred, and all patients who underwent video-assisted thoracoscopic surgery alone were discharged from the hospital on post-operative day 2 or 3. The estimated positive predictive value was 80%. All patients were alive, and seven of nine patients with metastasis were relapse-free, at a mean follow-up period of 17.9 months (range, 1-51). However, two patients had recurrence at 16 and 14 months after surgery for internal mammary lymph node relapse.

Conclusions: Radiotherapy is the standard treatment for suspected internal mammary lymph node metastasis detected using positron emission tomography/computed tomography; however, we could safely perform minimally invasive video-assisted thoracoscopic surgery resection, leading to a definite pathological diagnosis.