Can molecular subtyping replace axillary nodal status as prognostic marker in breast cancer?

Prevalence of Molecular Subtypes of Breast Cancer in India: a Systematic Review and Meta-analysis

In the last two decades, India has witnessed a substantial increase in the incidence of breast cancer and associated mortality. Studies on the prevalence of molecular subtypes of breast cancer in India have reported inconsistent results. Therefore, we conducted a systematic review of observational studies to document the prevalence of molecular subtypes of breast cancer. A complete literature search for observational studies was conducted in MEDLINE and EMBASE databases using key MeSH terms ((molecular classification) OR (molecular subtypes)) AND (breast cancer)) OR (breast carcinoma)) AND (prevalence)) AND (India). Two reviewers independently reviewed the retrieved studies. The screened studies satisfying the eligibility were included. The quality of included studies was assessed using the selected STROBE criteria. The overall pooled prevalence of luminal A, luminal B, HER2-enriched, and triple-negative breast cancer (TNBC) subtypes of breast cancer were 0.33 (95% CI 0.23-0.44), 0.17 (95% CI 0.12-0.23), 0.15 (95% CI 0.12-0.19), and 0.30 (95% CI 0.27-0.33), respectively. Subgroup analyses were performed by mean age of patients, time period, region, and sample size of the study. Among molecular subtypes of breast cancer, luminal A was the most prevalent subtype followed by TNBC, luminal B, and HER2-enriched subtypes. The overall prevalence of TNBC in India is high compared to other regions of the world. Additional research is warranted to identify the determinants of high TNBC in India. Differentiating TNBC from other molecular subtypes is important to guide therapeutic management of breast cancer.

Meta-Analysis of Prevalence of Triple-Negative Breast Cancer and Its Clinical Features at Incidence in Indian Patients With Breast Cancer

PURPOSE

Breast cancer is the most common cancer in women in India, with higher incidence rates of aggressive subtypes, such as triple-negative breast cancer (TNBC).

METHODS

A systematic review was performed to compute pooled prevalence rates of TNBC among patients with breast cancer, and clinical features at presentation were systematically compared with non-TNBC in an Indian cohort of 20,000 patients.

RESULTS

Combined prevalence of TNBC among patients with breast cancer was found to be on the higher side (27%; 95% CI, 24% to 31%). We found that the estrogen receptor (ER) expression cutoff used to determine ER positivity had an influence on the pooled prevalence and ranged from 30% (ER/progesterone receptor [PR] cut ff at 1%) to 24% (ER/PR cutoff at 10%). Odds for TNBC to present in the younger age-group were significantly higher (pooled odds ratio [OR], 1.35; 95% CI, 1.08 to 1.69), with a significantly younger mean age of incidence (weighted mean difference, -2.75; 95% CI, -3.59 to -1.92). TNBC showed a significantly higher odds of presenting with high grade (pooled OR, 2.57; 95% CI, 2.12 to 3.12) and lymph node positivity (pooled OR, 1.39; 95% CI, 1.21 to 1.60) than non-TNBC.

CONCLUSION

Systematic review and meta-analysis of 34 studies revealed a high degree of heterogeneity in prevalence of TNBC within Indian patients with breast cancer, yet pooled prevalence of TNBC is high in India. High proportions of patients with TNBC present with aggressive features, such as high grade and lymph node positivity, compared with patients without TNBC. We emphasize the need for standardized methods for accurate diagnosis in countries like India.

Prevalence of Triple-Negative Breast Cancer in India: Systematic Review and Meta-Analysis

Purpose

There is considerable variation in prevalence rates of triple-negative breast cancer (TNBC) reported by various studies from India. We performed a systematic review and literature-based meta-analysis of these studies.

Methods

We searched databases of Medline, Scopus, EMBASE, and Web of Science for studies that reported on the prevalence of TNBC in India that were published between January 1, 1999, and December 31, 2015. We extracted relevant information from each study by using a standardized form. We pooled study-specific estimates by using random-effects meta-analysis to provide summary estimates. We explored sources of heterogeneity by using subgroup analyses and metaregression.

Results

Data were obtained from 17 studies that involved 7,237 patients with breast cancer. Overall combined prevalence of TNBC was 31% (95% CI, 27% to 35%). There was substantial heterogeneity across the studies (I² of 91% [95% CI, 88% to 94%]; P < .001) that was not explained by available study level characteristics, including study location, definition of human epidermal growth factor receptor 2 or estrogen receptor, mean age of participants, proportion of patients with premenopausal cancer, grade 3 disease, or tumor size > 5 cm. Overall combined prevalence of hormone receptor–positive and human epidermal growth factor receptor 2–positive breast cancer was 48% (95% CI, 42% to 54%) and 27% (95% CI, 24% to 31%), respectively. There was no evidence of publication bias.

Conclusion

Prevalence of TNBC in India is considerably higher compared with that seen in Western populations. As many as as one in three women with breast cancer could have triple-negative disease. This finding has significant clinical relevance as it may contribute to poor outcomes in patients with breast cancer in India. Additional research is needed to understand the determinants of TNBC in India.

Prognostic analysis in a Chinese population with T1-2N1 breast cancer: Did patients with 1 or 2, and 3 positive axillary lymph nodes have similar survival outcomes?

BACKGROUND AND OBJECTIVES

There is a paucity of data examining whether 1-3 positive lymph nodes patients have similar survival outcomes. The present studies separately analyse survival outcomes of T1-2N1 breast cancer patients according to the number of positive lymph nodes.

METHODS

A total of 1,030 patients with T1-2N1 breast cancer were available for analysis. Survival estimates were calculated using the Kaplan-Meier method, univariate, and multivariate logistic regression models

RESULTS

Kaplan-Meier analysis showed progressively worse survival with the increased number of positive lymph nodes. Log-rank test P values were 0.003 (1 vs. 2 positive LNs), <0.0001 (1 vs. 3), and 0.006 (2 vs. 3) for recurrence-free survival (RFS). Log-rank test P values were 0.045 (1 vs. 2), <0.0001 (1 vs. 3), and 0.018 (2 vs. 3) for metastasis-free survival (MFS). Log-rank test P values were 0.101 (1 vs. 2), <0.0001 (1 vs. 3), and 0.005 (2 vs. 3) for overall survival (OS). Multivariate analysis showed that 3 and 2 positive lymph nodes had worse survival compared with 1 positive axillary lymph nodes.

CONCLUSIONS

Our study does suggest that T1-2N1 patients showed progressively worse survival outcomes with the increased number of positive lymph nodes.