2888 - Very Accelerated Partial Breast Irradiation (vAPBI) Delivered in Four Fractions: Prospective Feasibility Study Using Multi-Catheter Interstitial Brachytherapy in India
Presenter(s)
S. A. R. Swarna1, S. Shah1, P. Rana1, S. Nirala2, S. Bhasker1, D. N. Sharma3, S. Gupta1, K. P. Haresh4, S. Mallick5, A. Batra6, S. Bhoriwal7, and S. K. Saini8; 1All India Institute of Medical Sciences, New Delhi, India, 2All India Institute of Medical Sciences, New Delhi, Delhi, India, 3AIl India Institute of Medical Sciences, New Delhi, India, 4All India Institute Of Medical Sciences, New Delhi, India, 5National Cancer Institute, Jhajjar, Haryana, India, 6All India Institute of Medical Sciences, New Delhi, New Delhi, India, 7MCH Surgical Oncology, AIIMS New Delhi, Delhi, India, 8AIl India Institute of Medical Sciences, New Delhi, Delhi, India
Purpose/Objective(s): We evaluated a very accelerated partial breast irradiation (vAPBI) schedule completed in 4 fractions over 2 days using multi-catheter HDR interstitial brachytherapy. We hypothesized that this ultrashort regimen would be tolerable, with a low rate of grade =2 acute toxicity and acceptable cosmetic outcomes in carefully selected early-stage breast cancer patients of the Indian population.
Materials/Methods: This prospective feasibility study enrolled women =40 years of age with invasive carcinoma or DCIS =3.5 cm, node-negative, treated with breast-conserving surgery. vAPBI was delivered as 24.8 Gy in 4 fractions (6.2 Gy BID, =6-hour interval). The primary endpoint was acute skin toxicity (RTOG), with grade >2 events within 3 months defined as clinically significant, and local control. Secondary endpoint as cosmetic outcomes measured using Harvard 4-point scale.
Results: Twenty patients were treated and followed for a median of 10 months [range: 4-23], median age was 54 years [40-71]; median tumor size was 2.1 cm [1.2-3] and invasive ductal carcinoma in 80% of the patients. Around 40% of the patients received adjuvant chemotherapy and 85% received hormone therapy. Dosimetric goals were achieved with median CTV of 57.4 cc, median D90 of 25.8 Gy, V100 of 92.8%, V150 of 16.8 cc, V200 of 8.2 cc. Grade 1 acute dermatitis occurred in 8 patients (40%) at 1 month and grade 2 acute toxicity was observed in 2 patients (10%) which resolved with conservative management subsequently. No grade 3–4 acute toxicities were observed. Cosmetic outcomes were excellent in 60%, good in 30% and fair in 10% of the 20 evaluable patients with at least 3 months of follow-up. Of the 17 evaluable patients with a minimum of 6 months follow-up, cosmesis was excellent in 65%, good in 29% and fair in 6% of the patients. None of the patients had poor cosmetic outcomes during the follow-up period. No local, regional, or distant recurrences were observed during follow-up.
Conclusion: Four-fraction multi-catheter HDR vAPBI was feasible and well tolerated, with low rates of clinically significant acute toxicity and favorable early cosmetic outcomes with need of longer follow-up to assess late toxicity and durable local control. These preliminary results support the use of vAPBI in appropriately selected patients, especially in resource-constrained settings which will optimize brachytherapy units by shortening treatment time and thereby increasing overall treatment capacity.