Preliminary results of proton beam therapy for esophageal carcinoma
Presenter: Jiamin Li, Suwen Liu, Jianguang Zhang
Affiliation: Wanjie Proton Therapy Center, Zibo Wanjie Hospital, Boshan, Zibo, Shandong Province, China
- Esophageal cancer has historically been treated with a combination of surgery (when possible), photon radiotherapy, and chemotherapy
- Radiation therapy doses to the esophagus are limited by nearby critical structures including the spinal cord, lungs, and heart, which can lead to acute and chronic toxicities.
- Dose escalation in definitive radiation treatment of esophageal cancer is somewhat controversial, as the RTOG trial had excessive deaths on the high dose treatment arm (although several of these deaths were in patients that did not receive the full radiation dose). Currently used radiation doses are associated with poor local control.
- Proton radiotherapy offers a way to increase the total tumor dose (and hopefully local control) without excessive toxicity for definitive radiation treatment of esophagus cancer
- The feasibility of proton beam therapy for esophageal carcinoma was evaluated
Material and Methods
- 4 patients with esophageal carcinoma (age 50-82) were treated at the Wanjie Proton Therapy Center between 12/2004 and 1/2006
- Tumor length was determined by barium swallow, esophagoscopy, and PET-CT
- Pathology: 3 SCC and 1 adenocarcinoma
- 1: middle third, 8 cm, regional mediastinal LN
- 2: lower third, 5 cm, no regional LN
- 3: upper third, 4 cm
- 4: 82 yo with abdominal esophageal cancer, multiple gastric LN
- 2 patients were treated with a combination of photons and protons, 2 were treated with protons only
Fields: 2 fields, AP-PA were used. 3-4 cm beyond primary tumor cephalad and caudad lateral borders were 1-1.5 cm
Fractionation/Dose: 1.8 or 2.0 Gy for photon and proton, total dose 60 to 66 Gy
- Some sample DVH curves were presented, with excellent coverage of target volumes with relatively low dose to lung and spinal cord. Comparison with conventional photon plans was not presented.
- All patients completed treatment without interruption
- No esophageal ulcers were seen with 12 month follow up
- Radiation Esophagitis:
- Grade 1 in 3 patients
- Grade 2 in 1 patient
- 3 of 4 had a complete response within 3 months
- Patient 4 died of distant metastases 13 months later
- Patient 3 relapsed 12 months later
- Patients 1 and 2 are free of disease after >1 yr follow-up
- Proton beam radiation therapy was feasible, well-tolerated and effective for patient with esophageal cancer
- Proton beam therapy can spare more surrounding tissues such as lung, heart, and spinal cord
- Local control rates are comparable to those treated with conventional radiation therapy
- Acute toxicity is lower that that for conventional therapy, but more follow-up is needed for late effects
Clinical and Scientific Implications
- As proton therapy becomes more widespread, different malignancies will be treated with protons. Good dosimetry with AP-PA protons fields was demonstrated in this study, but a comparison with photon plans would have made this study more compelling.
- 1 of 4 patients had a local relapse, but the dose was not specified for this patient
- The use of concurrent chemotherapy was not specified in this study. The acute toxicities would likely be worse with concurrent chemotherapy.
- Dose escalation for definitive radiotherapy of the esophagus may be attempted with proton therapy, given the ability to spare normal structures.
- The use of proton therapy in the pre- or post-operative setting remains to be explored.