Impact of the Number of Cautionary and/or Unsuitable Risk Factors on Outcomes After Accelerated Partial Breast Irradiation

Omission of radiation therapy following breast conservation in older (≥70 years) women with T1-2N0 triple-negative breast cancer

BACKGROUND

Although randomized data support omitting adjuvant radiotherapy (RT) following breast conservation for T1-2N0 estrogen receptor positive breast cancer in ≥70-year-old women, there remains a knowledge gap regarding its omission for triple-negative BC (TNBC).

METHODS AND MATERIALS

The National Cancer Database (NCDB) was queried for ≥70-year-old females with newly diagnosed T1-2N0M0 TNBC treated with breast conservation. Multivariable logistic regression ascertained factors associated with adjuvant RT administration. Overall survival (OS) between patients treated with or without adjuvant RT was estimated using the Kaplan-Meier method. Cox proportional hazards modeling determined variables associated with OS.

RESULTS

Of 8526 patients, 6283 (74%) patients received adjuvant RT, and 2243 (26%) did not. RT was more frequently withheld in older patients, those with higher comorbidities, lower income, pT2 disease, following margin-positive resection, receipt of chemotherapy, and at academic centers (P < 0.05 for all). Median follow-up was 38.0 months. Five-year OS was greater in the adjuvant RT group (77.2% vs 55.3%, P < 0.001); these differences persisted when stratifying for age, T stage, and chemotherapy utilization (P < 0.001 for all). Omission of RT was also independently associated with poorer OS on multivariate analysis (P < 0.001).

CONCLUSIONS

This investigation, the largest known such study to date, observed that omission of adjuvant RT for elderly women with T1-2N0 TNBC was associated with poorer OS; this was observed across a range of age groups, as well as following stratification by T stage and chemotherapy usage. Although these results do not imply causation, caution must be exercised when considering omission of adjuvant RT in node-negative TNBC patients.

Seven-Year Outcomes Following Accelerated Partial Breast Irradiation Stratified by ASTRO Consensus Groupings

OBJECTIVES

Limited long-term data exist regarding outcomes for patients treated with accelerated partial breast irradiation (APBI), particularly, when stratified by American Society for Radiation Oncology (ASTRO) Consensus Statement (CS) risk groups. The purpose of this analysis is to present 5- and 7-year outcomes following APBI based on CS groupings.

MATERIALS AND METHODS

A total of 690 patients with early-stage breast cancer underwent APBI from 1993 to 2012, receiving interstitial brachytherapy (n=195), balloon-based brachytherapy (n=290), or 3-dimensional conformal radiotherapy (n=205) at a single institution. Patients were stratified into suitable, cautionary, and unsuitable groups with 5-year outcomes analyzed. Seven-year outcomes were analyzed for a subset with follow-up of ≥2 years (n=625).

RESULTS

Median follow-up was 6.7 years (range, 0.1 to 20.1 y). Patients assigned to cautionary and unsuitable categories were more likely to have high-grade tumors (21% to 25% vs. 9%, P=0.001), receive chemotherapy (15% to 38% vs. 6%, P<0.001), and have close/positive margins (9% to 11% vs. 0%, P<0.001). There was no difference in ipsilateral breast tumor recurrence at 5 or 7 years: 2.2%, 1.2%, 2.8% at 5 years (P=0.57), and 2.2%, 1.9%, 4.6% at 7 years (P=0.58) in the suitable, cautionary, and unsuitable groups, respectively. As compared with the suitable group, increased rates of distant metastases were noted for the unsuitable and cautionary groups at 5 years (P=0.04).

CONCLUSIONS

No differences in rates of ipsilateral breast tumor recurrence were seen at 5 or 7 years when stratified by ASTRO CS groupings. Modest increases in distant recurrence were noted in the cautionary and unsuitable groups. These findings suggest that the ASTRO CS groupings stratify more for systemic recurrence and may not appropriately select patients for whole versus partial breast irradiation.

Accelerated partial breast irradiation in the elderly: 5-year results of high-dose rate multi-catheter brachytherapy

Objective

To evaluate clinical outcome after accelerated partial breast irradiation (APBI) in the elderly after high-dose-rate interstitial multi-catheter brachytherapy (HIBT).

Methods and materials

Between 2005 and 2013, 70 patients underwent APBI using HIBT. Catheter implant was performed intra or post-operatively (referred patients) after lumpectomy and axillary sentinel lymph node dissection. Once the pathological results confirmed the indication of APBI, planification CT-scan was performed to deliver 34 Gy/10f/5d or 32 Gy/8f/4d. Dose-volume adaptation was manually achieved (graphical optimization). Dosimetric results and clinical outcome were retrospectively analyzed. Physician cosmetic evaluation was reported.

Results

With a median follow-up of 60.9 months [4.6 – 90.1], median age was 80.7 years [62 – 93.1]. Regarding APBI ASTRO criteria, 61.4%, 18.6% and 20% were classified as suitable, cautionary and non-suitable respectively. Axillary sentinel lymph node dissection was performed in 94.3%; 8 pts (11.5%) presented an axillary involvement. A median dose of 34 Gy [32 – 35] in 8 to 10 fractions was delivered. Median CTV was 75.2 cc [16.9 – 210], median D90 EQD2 was 43.3 Gy [35 – 72.6] and median DHI was 0.54 [0.19 – 0.74]. One patient experienced ipsilateral recurrence (5-year local free recurrence rate: 97.6%. Five-year specific and overall survival rates were 97.9% and 93.2% respectively. Thirty-four patients (48%) presented 47 late complications classified grade 1 (80.8%) and grade 2 (19.2%) with no grade ≥ 3. Cosmetic results were considered excellent/good for 67 pts (95.7%).

Conclusion

APBI using HIBT and respecting strict rules of implantation and planification, represents a smart alternative between no post-operative irradiation and whole breast irradiation delivered over 6 consecutive weeks.