Breast cancers in U.S. residing Indian-Pakistani versus non-Hispanic White women: comparative analysis of clinical-pathologic features, treatment, and survival

Abstract

South Asians from India and Pakistan represent one of the fastest growing immigrant populations in the US, yet there are limited data assessing breast cancers for this distinct ethnic sub-group. The aim of this study was to analyze clinical-pathologic, treatment and outcome characteristics of U.S.-residing Indian-Pakistani (IP) versus non-Hispanic white (NHW) female breast cancer patients to assess if any differences/disparities exist. The study cohort consisted of 2,393 IP and 555,832 NHW women (diagnosed 1988–2006) in the SEER database. Differences between the two populations were analyzed using chisquared and multivariate regression analysis. Age-adjusted incidence, mortality, and relative survival rates were calculated for the two groups. Significant differences in the characteristics of the IP cohort’s invasive disease included: younger median age at presentation; larger tumor size; higher stage, higher grade, more involved lymph-nodes, and more hormone receptor negative disease (all P < 0.01). The age-adjusted incidence and breast cancer mortality were lower in IP women. The relative survival at 5 years was statistically significant at 84% for IP versus 89% for NHW women, but was not significantly different on multivariate analysis (P > 0.05). Within each stage (Tis, I, II), there were no disparities in the rate of breast conservation surgery (BCS) or in the percentage of patients receiving adjuvant radiation after BCS for the 2 cohorts. Post-mastectomy radiation was delivered significantly more often in stage I/II IP patients undergoing mastectomy. In conclusion, this analysis suggests that while there appear to be significant differences in the features of breast cancers of US-residing IP women, no disparities were noted in the rates of breast conserving surgery or adjuvant radiation, as seen in some other ethnicities. The more aggressive clinical-pathologic features stage-for-stage in IP women may partially explain the more frequent use of post-mastectomy RT in this patient population. These findings warrant further investigation.

Comparative analysis of clinicopathologic features, treatment, and survival of Asian women with a breast cancer diagnosis residing in the United States

“…A lower percentage of Korean patients presented with stage IV disease, but they were more likely to have ER-negative and PR-negative disease. A higher percentage of Indian/Pakistani patients had stage III and IV disease but had a similar risk of mortality, consistent with a previous study by Moran et al 38 Unlike other studies, we observed that US-born Indian/ Pakistani patients had worse DSS than those born outside the United States. 39,40 Filipino patients had a similar DSS compared with Chinese, Korean, Indian/Pakistani, Vietnamese, and NHW patients, which differed from findings in a previously reported study by Ooi et al, who had a smaller sample size of Filipino patients in their study (4344 vs 10,915 in the current study).…”

Prevalence of TP53 germ line mutations in young Pakistani breast cancer patients

“…A recent analysis of breast cancer diagnoses using data from the United States National Cancer Institute's surveillance, epidemiology and end results (SEER) cancer program showed that Pakistani and Indian women in the US are more often diagnosed with breast cancer before age 40 than Caucasian women (16.2 vs. 6.2%) [2]. A similar finding was obtained in another study conducted among US-residing Pakistani/Indian immigrants that showed a higher proportion of breast cancers diagnoses before age 40 in Pakistani/Indian women compared to non-Hispanic White women (14.8 vs. 4.5%) [3].…”

The epigenetic silencing of the estrogen receptor (ER) by hypermethylation of the ESR1 promoter is seen predominantly in triple-negative breast cancers in Indian women

“…The few published reports suggest that TN breast cancer comprises approximately a quarter of all patients [7]. Interestingly this trend persists in women who have migrated from this region to the West [8,9]. Ours is not the only ethnic group to demonstrate this pattern, for similar trends have been reported in AfricanAmerican women [10][11][12].…”

“…The presence of a greater proportion of ER-negative and TN breast cancers in Indian women compared to Western White women has now been established beyond reasonable doubt [1][2][3][4][5][6][7][8][9]. However the biological basis of this difference remains to be worked out.…”

“…Earlier speculations that it might be due to demographic distributions or technical limitations of the immunohistochemistry testing are certainly mistaken. In fact the recent observations that women of Indian and Pakistani origin in USA continue to have a greater proportion of ER-negative cancers indicate that the causes are likely to be population and ethnicity related [8,9].…”