Proton Beam Therapy for Local Recurrence of Rectal Cancer

Abstract

Background/Aim: Curing local recurrence of rectal cancer (LRRC) is difficult with conventional photon radiotherapy. Proton beam therapy (PBT) on the other hand, has unique physical characteristics that permit higher doses to LRRC while minimizing side effects on surrounding organs. However, the efficacy of PBT on controlling rectal cancer recurrence has not yet been reported. This study aimed to evaluate clinical outcomes and toxicities of PBT for LRRC. Patients and Methods: Clinical outcomes were retrospectively evaluated for 12 patients with 13 total lesions that had received PBT for LRRC at our institute. Results: The median follow-up period from the initiation of PBT was 35.6 months. The 3-year local control, progression-free survival and overall survival rates were 80.2%, 10.4% and 73.8%, respectively. Median survival time was 67.1 months. There were no severe acute or late adverse events. Conclusion: PBT could be a safe and effective treatment method for LRRC.

Normofractionated and moderately hypofractionated proton therapy: comparison of acute toxicity and early quality of life outcomes

“…No difference in toxicity outcomes was observed with excellent QoL scores for the entire patient cohort ( 16 ). Other results of moderate hypofractionated PBT for prostate cancer and a single study on high-dose (75 Gy RBE in 25 fractions) definitive PBT for pelvic recurrences of colorectal adenocarcinoma reported very low rates of grade 2+ toxicities not exceeding 15%, comparable to the outcomes for abdominal and pelvic tumors of our series ( 17 – 19 ). The significantly better toxicity profile of hPBT compared to nPBT in our study can be possibly attributed to the lower EQD2 prescription dose used for most hPBT cases: for low-risk prostate cancer, which comprised the majority of patients in the group of abdominal and pelvic tumors, the assumed tumor α/β ratio was lower than one used to recalculate constraints for critical organs.…”

Proton Therapy in the Management of Luminal Gastrointestinal Cancers: Esophagus, Stomach, and Anorectum

“…In one study, 13 patients received 70 GyE in 25 fractions, resulting in a local control rate of 46% and only one G3/4 toxicity [ 87 ]. Another study retrospectively evaluated the outcomes of 12 patients who received PBT to LRRC [ 88 ]. With a median follow-up of 42.9 months, the 3-year PFS and OS rates were 12.1% and 71.3%, respectively, with no G 2+ acute or late toxicities noted.…”

Comparison of dosimetries of carbon-ion pencil beam scanning, proton pencil beam scanning and volumetric modulated arc therapy for locally recurrent rectal cancer

“…Surgical resection, chemotherapy and radiotherapy are the main treatment strategies for rectal cancer [ 2 ]. Recently, charged particle beam therapies, including those with proton beams [ 3–5 ] and carbon-ion beams [ 6–10 ], have been applied in rectal cancer treatment. The rates of local recurrence are approximately 5% and 11% for radiotherapy + surgery and surgery only, respectively [ 11 ].…”

“…Our carbon-ion beam facility has treated more than 13 000 patients since 1994 [ 12–15 ]. For locally recurrent rectal cancer treated with carbon-ion beam therapy, the overall survival rates have been 73% at 3 years and 51% at 5 years [ 16 ], compared with photon- and proton-beam treatments which had a 3-year overall survival of 64% and 71.3% and 5-year overall survival of 24.9% and 60% (as estimated from figures in [ 3 ]), respectively [ 3 , 17 , 18 ].…”