No abstract

Background: During embryogenesis, bilateral thickening of ectoderm from anterior axillary folds to inguinal folds, called mammary ridges or milk lines, develops into breast tissues. Only a pair in the pectoral area is spared from regression and continuously develops into normal breasts. Accessory breasts can result if the regression process is incomplete. These ectopic breasts can change physiologically and pathologically similar to normal breasts. Unsurprisingly, they are capable of turning malignant. Reported cases show the most common area for accessory breast cancer to be the axillary area. We report a rare case of accessory breast cancer over the costal ridge. Case presentation: We present the case of a 51-year-old Asian woman who complained of an enlarged mass lower to her left breast developed over the period of 3 months while on contraceptive pills. Unaware that the mass could be an accessory breast, the primary doctor had prescribed oral contraceptives. After our patient had noticed that the mass was obviously growing, she decided to consult a surgeon as the mass continued to grow. Expected to be benign, the mass was investigated by ultrasonography and then excised surgically. A pathology report identified the mass to be a carcinoma of the ectopic breast tissue. However, sentinel lymph node biopsy showed no nodal metastasis of all four lymph nodes. Following surgery, she received chemotherapy, radiation, and antihormonal treatment. After 2 years of postoperative follow up, she remained free of disease. Conclusions: This patient was diagnosed as having accessory breast cancer which presented with a subcutaneous mass. As this condition is exceptionally rare but curable by early treatments, we recommend surgeons to consider potential malignancy when patients present with a subcutaneous mass.

1039 Background: KAMILLA is an open-label, single-arm, phase 3b safety study of T-DM1 in pts with HER2-positive advanced BC (NCT01702571). The treated (safety) population of KAMILLA comprises 2 cohorts: a larger global Cohort 1 (n=2002) and a smaller Asia Cohort 2 (n=181 [China, n=154; Thailand, n=15; Indonesia, n=12]). Here we report results from Cohort 2 in the context of those previously reported for Cohort 1. Methods: Pts had HER2-positive, locally advanced or mBC with progression after chemotherapy and anti-HER2 therapy or ≤6 months (mo) of completing adjuvant therapy. T-DM1 3.6 mg/kg was given intravenously every 3 weeks until disease progression, consent withdrawal, or unacceptable toxicity. Primary endpoints were grade ≥3 (G≥3) adverse events of primary interest (AEPIs), specifically hepatic events, allergic reactions, thrombocytopenia (TCP), and hemorrhage events; all other G≥3 treatment-related AEs (TRAEs); and all-grade pneumonitis. Results: As of 31 July 2019,KAMILLA enrolled 2185 pts (Cohort 1, n=2003; Cohort 2, n=182), of which 2002 and 181 in each cohort, respectively, received ≥1 study dose and were included in the safety population. Baseline characteristics were generally similar between cohorts. Median (range) T-DM1 exposure was 5.6 mo (0–46) for Cohort 1 and 5.0 mo (0–31) for Cohort 2. The overall G≥3 AEPI rate was higher in Cohort 2 vs Cohort 1 (Table), mostly driven by a higher G≥3 TCP rate in Cohort 2. In Cohort 2, G≥3 TCP (the most frequently reported G≥3 AEPI) did not appear to be associated with G≥3 hemorrhagic events — the majority of G≥3 TCP events (128/138) fully resolved, with a duration of ≤15 days for 98/138 of these events. G≥3 TRAE rates were 18.4% in Cohort 1 and 48.6% in Cohort 2, the latter mainly due to TCP and platelet count decreased; any-grade pneumonitis rates were 1.0% and 2.2%, respectively. No other safety signals were identified. Median progression-free survival and overall survival were similar for both cohorts (Table). Conclusions: These data confirm prior observations in an Asian subgroup of the phase 3 EMILIA trial of T-DM1 in pts with previously treated mBC. Although the G≥3 TCP rate was higher in the Asia cohort, the majority of these events resolved fully. OS and PFS were similar in both cohorts. These data reinforce the favorable T-DM1 benefit-risk profile in mBC. Clinical trial information: NCT01702571 .[Table: see text]

Background: Whole breast irradiation after breast-conserving surgery (BCS) with an external beam boost of 10-16 Gy is currently the standard treatment in breast cancer. Various modalities have been used for tumor bed boost irradiation. This study aimed to evaluate the local recurrence rate, overall survival rate (OSR), toxicity and cosmetic outcome of intraoperative radiotherapy (IORT) as a boost followed by whole breast irradiation in patients who received BCS.Methods: This is a retrospective study. Between December 2009 and March 2017, 81 patients who underwent BCS with IORT as a boost were enrolled in this study. For IORT, a single dose of 20 Gy was delivered using a 30-50 kV photon beam, intraoperatively. All patients received whole breast radiation therapy (WBRT) of 42.5-50 Gy over 4-5 weeks. The primary endpoint was a 3-year local recurrence rate. Secondary endpoints included the OSR, toxicity and cosmetic outcome at 6 months after radiation treatment.Results: At a median follow-up of 43 months, ipsilateral local recurrence was observed in one of the 81 patients (1.2%) which occurred in the same quadrant of the breast index. The 3-year OSR was 89.8%.Treatment was well-tolerated with no grade 3-4 acute and late toxicity, and 87% of patients were recorded as excellent-good cosmesis.Conclusions: The use of BCS with IORT as a boost resulted in a low local recurrence rate and excellent cosmetic outcome in early breast cancer. Thus, IORT as a boost could be considered as an alternative to an external beam boost. Prospective studies are needed to confirm this data.

Clinical application of the ACOSOG Z0011 trial results allows clinically node-negative breast cancer patients who meet criteria to avoid axillary dissection even when 1-2 sentinel lymph nodes (SLNs) are positive for metastatic disease. Intraoperative frozen section (iFS) analyses of SLNs were thought to reduce re-operation rates despite variable reported sensitivity and possibility of a false negative result. This study evaluated the rate of re-operations prevented by SLN iFS in a tertiary care hospital in Bangkok, Thailand, over a 6-year time-frame. Patients and Methods:From April 2016 to April 2022, 1284 sentinel lymph node biopsy (SLNB) procedures were performed. Of these, 214 cases were breast-conserving surgery in accordance with the ACOSOG criteria with concomitant usage of iFS. Clinicopathological features of these cases were collected and analyzed. Re-operation rates prevented by the additional intervention were reported. Results: Only five additional operations were prevented with the usage of 214 iFS. The discordance rate between frozen and permanent sections in terms of presence of metastatic disease and number of total lymph nodes was around 15%. Tumor staging, node staging, Nottingham histologic grading and lymphovascular invasion are significant predictors of SLN metastasis. Conclusion: iFS results in a very low prevention rate for follow-up ALND in patients with preoperative clinically negative axillary nodes and is associated with a non-negligible discordance rate with permanent sections. Our study suggests iFS may be avoided in most cases of early-stage clinically and radiographically node-negative breast cancer patients. Doing so may reduce surgical costs and total operative time without a significant impact on the overall quality of treatment and standard of care.