Long Term Outcomes Comparing Three-Dimensional Conformal Radiation Therapy to Intensity Modulated Radiation Therapy with Concurrent Chemotherapy for the Treatment of Esophageal Cancer: The MD Anderson Experience
The Abramson Cancer Center of the University of Pennsylvania
Last Modified: October 4, 2011
Presenter: BA Myles
Presenter Affiliation: MD Anderson Cancer Center, Houston, TX
- 3D-CRT with concurrent chemotherapy (pre-operative or definitive) is the standard of care for treating patients with esophageal cancer.
- However, with 3D-CRT, there is concern for toxicity to adjacent structures, mainly lung and heart. Keeping this concern in mind, IMRT has been used as an alternative, which offers a dosimetric advantage over 3D-CRT in regards to organs at risk.
- There is no randomized data available comparing the two modalities. It is unclear what the dosimetric advantages of IMRT may mean for clinical symptoms experienced by patients.
- Authors retrospectively evaluated patients treated at MD Anderson Cancer Center between 1998-2010 who got concurrent chemo-radiation therapy for esophageal cancer.
- Toxicity data consisting of nausea, esophagitis, pneumonitis, anorexia, dysphagia and weight loss was collected for all patients.
- Endpoints evaluated were local control, distant metastasis, disease free survival, overall survival and acute and late toxicities.
- There were 398 patients who got 3D-CRT and 301 who got IMRT.
- Baseline characteristics of patients in both groups were similar except that there were more patients in the IMRT group that had PET staging. About 90% of patients in the IMRT group were PET staged vs 50% of patients in the 3D-CRT group.
- In terms of chemotherapy, more patients in 3D-CRT group received induction chemotherapy and triplet chemotherapy and more patients in IMRT group received doublet chemotherapy.
- In regards to toxicity, more patients in 3D-CRT group had >10% weight loss. There was no other difference in toxicity outcomes evaluated (esophagitis, pneumonitis, PEG-tube placement etc.)
- Risk factors associated with poor survival outcomes on multivariate analysis were poor performance status, not getting induction chemotherapy, concurrent chemoRT, treatment with 3D-CRT and stage II-III disease.
- There was a significant increase in survival in IMRT arm-- OS of 42.4% arm vs 31.3% at 5 years and median survival of 36 months vs 24 months (SS) in IMRT vs 3D-CRT arms respectively.
- There was no difference in freedom from distant failure and local failure.
- Cause specific deaths were compared in the IMRT and 3D-CRT arms. There was no difference in cancer specific death or pulmonary death in the two arms. However, there were significantly more cardiac deaths and deaths due to unknown causes in the 3D-CRT arm.
- No difference in toxicity in the IMRT and 3D-CRT.
- There is no difference in distant or local disease control in the two arms.
- However, patients treated with IMRT have higher overall survival compared to patients treated with 3D-CRT. This could be because of normal tissue sparing by IMRT may lead to reduction in death from cardiac causes or other unknown (non-cancer) causes.
Clinical and Scientific Implications
- There are a few limitations to this study: it is a retrospective analysis and it is unclear what patients are dying of in the unknown group.
- Given these limitations and the fact that there is no significant outcome difference in the two groups, 3D-CRT will remain standard of care for esophageal cancer. Use of IMRT will continue to be an option for patients when constraints to organs at risk are not met using 3D-CRT treatment planning. Value of increased overall survival in IMRT arm is hard to interpret in a retrospective analysis where there may be various other unknown variables contributing to increased survival.