“This makes one think about using radiation therapy with high risk features, but one has to be careful when using retrospective data when changing clinical practice,” Dr. Pawlik said in an interview with Cancer Therapy Advisor. “We used propensity matching to minimize bias, but we can’t get rid of the bias entirely.”

He said this is an understudied area and he hopes these findings will lead to further investigations by other researchers. Co-study author Ryan Fields, MD, who is an assistant professor of surgery at Washington University School of Medicine in St. Louis, MO, said other issues that need to be investigated are the costs and increased morbidity that may be associated with chemoradiation versus chemotherapy alone.


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“The side effect profile of chemoradiotherapy and chemotherapy are well known and reported in other studies. This study did not look at a risk benefit ratio. Costs would be expectedly higher for adding radiation. The main point of this analysis is really that chemoradiotherapy works well in patients selected for this treatment modality,” Dr. Fields told Cancer Therapy Advisor.

Bapsi Chakravarthy, MD, who is the Program Director of Radiation Oncology at Vanderbilt University in Nashville, TN, said randomized studies have compared perioperative chemotherapy to surgery alone and postoperative chemoradiation to surgery alone.

However, there are no randomized trials that have compared perioperative chemotherapy to postoperative chemoradiation.

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She said although the current investigation is a well done retrospective analysis that has tried to balance the baseline characteristics of these two groups using propensity score matching, it is not clear if the differences seen in the two groups may still be a result of selection bias.

“Patients who received chemoradiation may be the younger, healthier patients who would do well regardless of the type of treatment they received. Although this study will not change current clinical practice, it provides more evidence that this question needs to be addressed in a larger randomized study,” Dr. Chakravarthy told Cancer Therapy Advisor.

Currently, gastric cancer is the 16th most commonly diagnosed cancer in the United States and approximately 22,220 new cases are expected to be diagnosed in 2014 and 10,990 patients are expected to die.3

The 5-year survival rate is estimated to be 28.3%. Because the mortality rates remain so high it is important to identify which subset of patients after surgical resection of gastric adenocarcinoma may benefit the most from chemoradiation.

References

  1. Ejaz A, Spolverato G, Kim Y, et al. Impact of external-beam radiation therapy on outcomes among patients with resected gastric cancer: a multi-institutional analysis. Ann Surg Oncol. 2014;21(11):3412–3421.
  2. Bamias A, Karina M, Papakostas P, et al. A randomized phase III study of adjuvant platinum/docetaxel chemotherapy with or without radiation therapy in patients with gastric cancer. Cancer Chemother Pharmacol. 2010;65(6):1009-1021.
  3. SEER Stat  Facts Sheets: Stomach Cancer. National Cancer Institute. http://seer.cancer.gov/statfacts/html/stomach.html. Accessed December 4, 2014.