B.H. Chon

Early toxicity in patients treated with postoperative proton therapy for locally advanced breast cancer.

PURPOSE To report dosimetry and early toxicity data in breast cancer patients treated with postoperative proton radiation therapy. METHODS AND MATERIALS 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.

Anterior-oriented proton beams for prostate cancer: A multi-institutional experience.

Abstract 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. 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. 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.

Patient-reported Quality of Life After Proton Beam Therapy for Prostate Cancer: The Effect of Prostate Size

Micro‐Abstract The present study assessed the effect of prostate gland size on patient‐assessed quality of life (QOL) after definitive treatment of prostate adenocarcinoma with proton beam therapy. A larger prostate size, despite receiving a greater radiation dose, did not affect QOL at 6 months, providing further support that neoadjuvant cytoreductive treatments are unnecessary. Background: In the present study, we assessed the effect of prostate gland size on patient‐assessed genitourinary and gastrointestinal (GI) quality of life (QOL) after definitive treatment of prostate adenocarcinoma with proton beam therapy. Patients and Methods: As a part of a prospective outcome tracking protocol, 81 patients treated at a single center between with proton beam therapy completed the Expanded Prostate Cancer Index Composite (EPIC) questionnaire before treatment and at the follow‐up examinations. We reviewed the dosimetric data, reported as Vx (volume of organ receiving x Gy), and patient‐reported QOL at 6 months. Genitourinary QOL was assessed using the American Urological Association symptom score and EPIC urinary domain score. GI QOL was assessed using the EPIC GI domain score. Results: Larger prostate glands were associated with greater bladder V70 (P < .01) and rectal V70 (P < .01). The rectal V70 was < 15% for all patients (range, 4%‐13.8%) with the planned treatment volume coverage (percentage of the prescription dose covering 95% of the volume > 95%) maintained. Patients with larger prostates did not have a greater change in their American Urological Association symptom index scores (< 30 cm3, +2.3; 30‐49 cm3, +3.2; ≥ 50 cm3, 0.2; P = .06) or urinary domain score (< 30 cm3, −3.6; 30‐49 cm3, −3.1; ≥ 50 cm3, +3.8; P = .76) at 6 months after treatment. Also, prostate size was not associated with a change in the EPIC GI domain score at 6 months after treatment (< 30 cm3, −3.7; 30‐49 cm3, −1.1; ≥ 50 cm3, −0.55; P = .67). Conclusion: Definitive proton beam therapy for prostate cancer to a dose of 79.2 Gy resulted in excellent patient‐reported urinary and GI QOL, independently of the baseline prostate size. This single‐institution finding should be tested further in a multi‐institutional study to confirm the potential limited role of androgen deprivation therapy.