Ongoing phase III trials are comparing accelerated PBI around the lumpectomy site to standard whole breast irradiation in early stage breast cancer. Recent studies have questioned the late toxicity from PBI delivered with 3DCRT. We evaluated late toxicity on patients (pts) treated on RTOG 0319.

Methods:52 pts with stage I-II breast cancer, ≥3 cm, negative margins, and < 3 nodes positive were treated with 3DCRT PBI and received 38.5 Gy in 10 BID fractions over 5 days. Median follow-up was 5.3 years (min-max: 1.7-6.4 years). Five pts were deceased at 5 years. NCI CTCAE v3.0 was used to grade adverse events (AEs). At 3 years, 50 pts were available for AE reporting or late toxicity assessment.

Results: The treatment-related AEs were primarily grade 1 36.5%, 50% grade 2, and only 3 (5.8%) pts had grade 3 AEs. The grade 3 AEs in these pts were radiation dermatitis, skin fibrosis, telangectasia, and myositis. No baseline self-assessment of breast appearance is available. Patient self-assessment of breast appearance and satisfaction was available in 45 (87%) pts at 1 year and 36 (72%) at 3 years. At 1 year, 82% self reported excellent/good breast appearance and at 3 years, 64%. Pts who reported < excellent/good breast appearance had significantly more grade ≥2 skin AEs (telangectasia, skin atrophy, hyperpigmentation, erythema, skin fibrosis, radiation dermatitis, and breast or nipple/areolar deformity). At 3 years, 31 of 36 pts were satisfied with their treatment, but all 36 would choose 3DCRT PBI again over standard breast RT. Treatment factors were evaluated to establish correlation with patient reported breast appearance. Preliminary observations suggest surgical bed volume, PTV volume, number of beams used, and possible use of bolus are associated with patient reported outcomes (PRO). Surgical factors impacting PRO were not collected.

Conclusions: The majority of pts were satisfied with their treatment results at 3 years and would all choose to have 3DCRT PBI again. With a median of 5.3 years, the rate of grade 3 AEs is low. Technical factors from this phase II trial were modified for the phase III NSABP B-39/RTOG 0413 trial, in which bolus is not allowed and both target volumes and required coverage were modified, increasing expectation of improved PRO. Supported by RTOG U10 CA21661, CCOP U10 CA37422 and ATC U24 CA 81647 NCI grants.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-15-07.