Faculty Bibliography

PURPOSE/OBJECTIVE:To report dosimetry and early toxicity data in breast cancer patients treated with postoperative proton radiation therapy. METHODS AND MATERIALS/METHODS:From March 2013 to April 2014, 30 patients with nonmetastatic breast cancer and no history of prior radiation were treated with proton therapy at a single proton center. Patient characteristics and dosimetry were obtained through chart review. Patients were seen weekly while on treatment, at 1 month after radiation therapy completion, and at 3- to 6-month intervals thereafter. Toxicity was scored using Common Terminology Criteria for Adverse Events version 4.0. Frequencies of toxicities were tabulated. RESULTS:Median dose delivered was 50.4 Gy (relative biological equivalent [RBE]) in 5 weeks. Target volumes included the breast/chest wall and regional lymph nodes including the internal mammary lymph nodes (in 93%). No patients required a treatment break. Among patients with >3 months of follow-up (n=28), grade 2 dermatitis occurred in 20 patients (71.4%), with 8 (28.6%) experiencing moist desquamation. Grade 2 esophagitis occurred in 8 patients (28.6%). Grade 3 reconstructive complications occurred in 1 patient. The median planning target volume V95 was 96.43% (range, 79.39%-99.60%). The median mean heart dose was 0.88 Gy (RBE) [range, 0.01-3.20 Gy (RBE)] for all patients, and 1.00 Gy (RBE) among patients with left-sided tumors. The median V20 of the ipsilateral lung was 16.50% (range, 6.1%-30.3%). The median contralateral lung V5 was 0.34% (range, 0%-5.30%). The median maximal point dose to the esophagus was 45.65 Gy (RBE) [range, 0-65.4 Gy (RBE)]. The median contralateral breast mean dose was 0.29 Gy (RBE) [range, 0.03-3.50 Gy (RBE)]. CONCLUSIONS:Postoperative proton therapy is well tolerated, with acceptable rates of skin toxicity. Proton therapy favorably spares normal tissue without compromising target coverage. Further follow-up is necessary to assess for clinical outcomes and cardiopulmonary toxicities.

BACKGROUND:Proton beam therapy (PBT) for prostate cancer generally involves the use of two lateral beams that transverse the hips. In patients with hip replacements or a previously irradiated hip, this arrangement is contraindicated. The use of non-lateral beams is possible, but not well described. Here we report a multi-institutional experience for patients treated with at least one non-lateral proton beam for prostate cancer. MATERIAL AND METHODS/METHODS:Between 2010 and 2014, 20 patients with organ-confined prostate cancer and a history of hip prosthesis underwent proton therapy utilizing at least one anterior oblique beam (defined as between 10° and 85° from vertical) at one of three proton centers. RESULTS:The median follow-up was 6.4 months. No patients have developed PSA failure or distant metastases. The median planning target volume (PTV) D95 was 79.2 Gy (RBE) (range 69.7-79.9). The median rectal V70 was 9.2% (2.5-15.4). The median bladder V50, V80, and mean dose were 12.4% (3.7-27.1), 3.5 cm3 (0-7.1), and 14.9 Gy (RBE) (4.6-37.8), respectively. The median contralateral femur head V45 and max dose were 0.01 cm3 (0-16.6) and 43.7 Gy (RBE) (15.6-52.5), respectively. The incidence of acute Grade 2 urinary toxicity was 40%. There were no Grade≥3 urinary toxicities. There was one patient who developed late Grade 2 rectal proctitis, with no other cases of acute or late ≥Grade 2 gastrointestinal toxicity. Grade 2 erectile dysfunction occurred in two patients (11.1%). Mild hip pain was experienced by five patients (25%). There were no cases of hip fracture. CONCLUSION/CONCLUSIONS:PBT for prostate cancer utilizing anterior oblique beam trajectories is feasible with favorable dosimetry and acceptable toxicity. Further follow-up is needed to assess for long-term outcomes and toxicities.

PURPOSE/OBJECTIVE:To develop a nomogram based on clinicopathologic factors to quantify the risk of local recurrence (LR) after limb-sparing surgery without adjuvant radiation (RT). METHODS:Review of our prospective sarcoma database identified 684 patients with primary, nonmetastatic, extremity STS treated with limb-sparing surgery alone between June 1982 and December 2006. No patient received adjuvant radiation or chemotherapy. Age, sex, grade, depth, size, site, margin status and histology were analyzed for prognostic significance with respect to local recurrence rates using Gray's test. Variables which were significant in univariate analysis at the 0.05 level were entered into a multivariate competing risk regression model. On the basis of the multivariate analysis, a nomogram for predicting the 3- and 5-year risk of LR was developed using R libraries cmprsk and QHScrnomo. Concordance index (C-index) was calculated to evaluate the discriminatory power of the prognostic model. RESULTS:With a median follow-up of 58 months for censored patients (73 months for all patients), the overall 3- and 5-year actuarial local recurrence rates were 11% and 13%, respectively. Factors included in the nomogram were age (≤ 50 vs. >50), size (≤ 5 vs. >5 cm), margin status (negative vs. positive), grade (low vs. high), and histology (atypical lipomatous tumor/well differentiated liposarcoma vs. other). The STS nomogram predicted the local recurrence rate with a C-index of 0.73. CONCLUSIONS:A nomogram for extremity STS that includes age, size, margin status, grade of tumor, and histology predicts the 3- and 5-year risk of local recurrence after limb-sparing surgery in the absence of adjuvant RT.