Optimal radiotherapy for patients with internal mammary lymph node metastasis from breast cancer

Abstract

Background: This study aimed to determine the optimal radiotherapy (RT) regimen for patients with clinical metastasis to the internal mammary lymph node (cIMN+) from breast cancer. Methods: We retrospectively reviewed the medical records of 84 patients with cIMN+ breast cancer treated with curative surgery, taxane-based chemotherapy, and postoperative RT between January 2009 and December 2014. Postoperative RT was administered to the whole breast or chest wall using 50 Gy in 2 Gy fractions. Boost RT to the internal mammary lymph node (IMN) was administered at the physician's discretion. We categorized patients into two groups according to the IMN dose as follows: low-dose IMN RT (50.0-63.5 Gy) and high-dose IMN RT (63.6-70.4 Gy). Results: After a median follow-up of 58 months (range, 12-111 months), IMN recurrence was observed in 2 patients (2.4%), and all IMN recurrences developed simultaneously with distant metastases. The 5-year locoregional recurrence-free survival, disease-free survival (DFS), and overall survival rates were 89.1, 72.0, and 81.2%, respectively. The triple-negative subtype, IMN size ≥1.0 cm, old age, and low-dose IMN were significantly associated with poor DFS. Among the patients with IMN size ≥1.0 cm, the 5-year DFS was significantly higher in those treated with high-dose IMN RT than in those treated with low-dose IMN RT (69.3% vs. 33.3%, p = 0.019). Conclusions: IMN RT without IMN dissection resulted in favorable outcomes in cIMN+ breast cancer. For patients with a large IMN, a higher IMN radiation dose might be needed for disease control.

Prognostic significance of the primary tumor site and immune indexes in patients with estrogen receptor-positive, human epidermal growth factor receptor-2-negative breast cancer

“…The only feasible treatment for residual IMN metastasis is IMN-RT. In their study, Yang et al concluded that the IMN-RT was particularly suitable for patients with larger IMN (17). In their study, Aleknavičius et al found that IMN-RT was correlated with a better survival outcome for patients with moderate-risk disease (stage T1-2N1), and showed no association for better survival for high-risk disease (stage T3-4N2-3) (18).…”

Outcome of radiotherapy for clinically overt metastasis to the internal mammary lymph node in patients receiving neoadjuvant chemotherapy and breast cancer surgery

“…Further, IMNþ was mostly determined by radiologic examinations; only 2%e57% of the participants were diagnosed with IMN þ by both radiologic findings and histopathologic evaluation of the IMN. In addition, a radiation dose of 45.0e66.5 Gy was administered to the IMN chains, and the amount of IMN radiation dose was determined at the discretion of the physician [8,11,12,14] or the IMN response to NAC [26]. In a study by Zhang et al a dose of 66 Gy was prescribed to the IMN region in patients with residual radiographic IMN adenopathy after NAC, while and IMN dose of 60 Gy was given to patients showing complete radiologic response after NAC [26].…”

“…Contrary to the study of Park et al another study showed a significant association between IMN radiation dose and breast cancer survival. In a study by Yang et al the DFS was significantly influenced by the IMN dose in patients with large IMN adenopathy (!1 cm) [8]. The 5-year DFS in patients receiving a high IMN EQD2 (!63.6 Gy) and low IMN EQD2 (<63.6 Gy) was 69.3% and 33.3%, respectively (p < 0.01).…”

“…Although the IMN is defined as a regional node similar to the ALN, previous studies have suggested that breast cancer involving IMN has a worse prognosis than that involving ALN metastasis [5,6]. Nonetheless, in studies in which breast surgery and effective adjuvant treatments were administered, patients with IMN þ breast cancer could achieve favorable outcomes [7,8]. Although there are controversies regarding the negative prognostic influence of IMNþ, there is increasing need to optimize management for IMN þ breast cancer.…”

Excluding Lung Tissue from the PTV during Internal Mammary Irradiation. A Safe Technique for OAR-Sparing?

“…Instead of reducing the PTV margin, reduction of the prescribed to 45 Gy for the IMN can be discussed in patients with lower risk factors. For patients with IMN positive lymph nodes, however, there is emerging evidence that IMN irradiation with higher doses (IMNI ≥ 63.6 Gy or boost-RT to metastases) is associated with a better DFS compared to lower doses (50.0–63.5 Gy) and excellent IMN control [ 33 ]. This emphasizes the particular importance of adequate dose coverage and sufficient PTV-margins in these patients.…”