Relative Outcomes for Asian-Americans with Gastric Adenocarcinoma

Reviewer: Christine Hill, MD
The Abramson Cancer Center of the University of Pennsylvania
Ultima Vez Modificado: 22 de enero del 2009

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Presenter: B.A. Mailey, City of Hope, Duarte, CA

Background

  • Reported outcomes for patients with gastric cancer have historically been better in Japan and other Asian countries than in the United States and Europe.
    • These differences have been widely discussed. Although surgical differences may potentially have an impact, efforts in the US to replicate surgical treatment techniques from non-Asian countries have still not resulted in outcomes comparable to those reported from Asia.
  • Racial disparities in the development of and survival from many cancers have been demonstrated; overall, African-American patients may fare worse after diagnosis of breast cancer, leukemias, and esophageal cancers, while overall survival may be improved for Asian patients with certain malignancies when compared to non-Asian counterparts.
  • Reports have demonstrated improved survival for Asian patients with gastric cancer as opposed to non-Asians.

    • Among gastric cancer patients living in the United States, overall and median survival have been demonstrated to be improved for Asian-Americans versus Caucasians, Hispanics, and African-Americans (Al-Refaie et al, Cancer, 2008).
    • Improved survival has been demonstrated to persist for up to 5 years from diagnosis (Wang SJ, Gastric Cancer, 2004).
    • Differences in treatment characteristics have been speculated to play a role in improved outcomes.
    • Exposures, such as diet and infection with Heliobacter pylori, have been suggested to contribute to varied risk of development of gastric cancer, as well as response to treatment and risk of mortality.
  • The study presented here was carried out in order to investigate potential racial disparities in survival from gastric cancer in a heterogeneous United States population.

Methods

  • The Comprehensive California Cancer Registry of the Los Angeles County Cancer Surveillance Program was used to identify patients diagnosed with or treated for gastric adenocarcinoma in Los Angeles county hospitals between 1988 and 2006.
  • Patients were characterized by race as Asian, White, Black, or Hispanic.
  • Clinical and pathologic characteristics were analyzed, including tumor site, stage, grade, chemotherapy, radiotherapy, and surgical treatments.
  • Survival differences between races were compared using a Cox proportional hazard ratio.

Results

  • 13,529 gastric cancer patients were identified.
    • Of these, 42% (n = 5641) were White, 20% (n = 2753) were Asian, 25% (n = 3367) were Hispanic, 11% (n = 1531) were Black, and 1.8% (n = 237) were other races.
    • Median survival was significantly improved for Asian patients versus other races:
      • 15.8 months for Asian patients, 8.3 months for Whites, 7.8 months for Blacks, and 8.5 months for Hispanics, p < 0.001 for all comparisons.
    • On multivariate analysis, Asian race was associated with improved chance of survival when controlling for age, sex, tumor site, stage, grade, chemotherapy, radiotherapy, and surgery.
      • The hazard ratio for death for Asians versus non-Asians was 0.76 (95% CI 0.72-0.8, p < 0.001).
  • Of all 13,529 patients, 55.7% (n = 7529) underwent surgical resection, and Asian patients appeared to fare better following surgical resection compared to patients of other races.
    • Median survival was significantly longer for Asians following surgery versus non-Asians: 31.5 months for Asians, 17.6 months for Whites, 17.8 months for Blacks, and 19.1 months for Hispanics, p < 0.001 for all comparisons.
    • On Cox regression analysis, Asian patients had a better chance of survival after surgery compared to non-Asians, with hazard ratio for death of 0.79 (95% CI 0.73 – 0.85, p < 0.001).

Authors' Conclusions

  • The authors conclude that Asian-Americans with gastric adenocarcinoma have outcomes superior to White, Black, and Hispanic gastric cancer patients.
  • They note that this improved survival seems unrelated to surgical technique, and that survival disparities may result from other factors.

Comments

  • This study represents an interesting analysis of a large, heterogeneous population of patients treated for gastric cancer in the United States.
  • The authors confirm conclusions that have been suggested by other groups – namely, that gastric cancer patients of Asian descent appear to fare better than non-Asians, even when treatments are similar.
  • These findings may explain, in part, outcome differences reported from Japan and other Asian countries for gastric cancer patients versus those from the United States and Europe.
  • This study is limited by its use of a cancer registry for this analysis. Limited treatment details are available for individual patients, and treatment techniques and quality may vary based on institution.
  • Even so, this study examines a large group of patients, hopefully minimizing the impact of small differences in individual treatments.
  • The data presented here raise questions regarding genetic and exposure differences that may contribute to improved outcomes for Asian patients versus non-Asians.
  • Additionally, among subsets of Asian populations, both gastric cancer incidence and risk factors associated with gastric cancer have been demonstrated to be extremely variable. As an example, gastric ulcers and atrophic gastritis have been shown to affect Japanese patients more often than other Asian subsets (Matsuhisa T, KUMJ, 2007).
  • The findings presented here, in combination with those demonstrated by other groups, suggest that a real biologic difference may account for improved outcomes for Asian patients after gastric cancer, and that these differences may vary across Asian subsets. Further investigation into variable genetic and exposure factors would certainly be of interest, and could contribute to improved patient care and determination of necessary treatments.



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