Elsevier

Annals of Epidemiology

Volume 23, Issue 9, September 2013, Pages 551-557
Annals of Epidemiology

Risk factors for pregnancy-associated breast cancer: a report from the Nigerian Breast Cancer Study

https://doi.org/10.1016/j.annepidem.2013.06.008Get rights and content

Abstract

Purpose

Little is known about risk factors for pregnancy-associated breast cancer (PABC), diagnosed during pregnancy or postpartum.

Methods

We enrolled 1715 premenopausal women from the Nigerian Breast Cancer Study from 1998 to 2011. Based on recency of last pregnancy from diagnosis, breast cancer cases were categorized as (1) PABC diagnosed 2 years or longer postpartum, (2) PABC diagnosed 3 to 5 years postpartum, or (3) non-PABC diagnosed more than 5 years postpartum. Controls were matched to cases on recency of last pregnancy. Multiple logistic regressions were performed comparing cases and controls within each group.

Results

Of the 718 cases, 152 (21.2%) had PABC 2 or more years postpartum, and 145 (20.2%) 3 to 5 years postpartum. Although not statistically significant, women with higher parity tend to have an elevated risk of PABC but reduced risk of non-PABC (p for heterogeneity = 0.097). Family history of breast cancer might be a strong predictor particularly for PABC 2 or more years postpartum (odds ratio, 3.28; 95% confidence interval, 1.05–10.3). Compared with non-PABC cases, PABC 2 or more years postpartum cases were more likely to carry BRCA1/2 mutations (P = .03).

Conclusions

Parity may have different roles in the development of PABC versus other premenopausal breast cancer in Nigerian women. Prospective mothers with multiple births and a family history of breast cancer may have an elevated risk of breast cancer during their immediate postpartum period.

Section snippets

Study sample

The Nigerian Breast Cancer Study is a case-control study conducted in Ibadan, Nigeria, from 1998 to 2011. The study setting and design were described in detail elsewhere [26], [27]. Briefly, cases were identified through University College Hospital (UCH) in Ibadan. Serving a population of approximately 3 million, UCH is a referral center for other hospitals and thus treats the majority of breast cancer cases in the region. All consecutive female cases aged 18 years and older with a histologic

Results

In all, 1715 premenopausal women were included in this study: 297 PABC cases (152 within 2 years postpartum, 145 between 3 and 5 years postpartum), 421 non-PABC cases, and 997 healthy controls (282 were ≤2 years postpartum, 188 were 3–5 years postpartum, and 525 were ≥5 years postpartum). Cases were significantly older than their matched controls (P ≤ .01), and non-PABC cases were older than PABC cases (P < .0001; Table 1). The age difference between PABC and non-PABC is expected because

Discussion

Using data from an understudied African population, we examined risk factors for premenopausal breast cancer according to childbearing recency. To our knowledge, this is the first study that explicitly examines risk factors associated with PABC, and we collected comprehensive pregnancy data in a unique Nigerian cohort spanning more than a decade. We hypothesized that PABC is more likely to be observed in our study owing to the strong culture of high parity in Nigeria. Different tumor

Acknowledgment

This work was supported in part by National Cancer Institute (R01 CA89085, P50 CA125183).

References (58)

  • M. Lambe et al.

    Transient increase in the risk of breast cancer after giving birth

    N Engl J Med

    (1994)
  • J.A. Petrek

    Breast cancer during pregnancy

    Cancer

    (1994)
  • J.C. Woo et al.

    Breast cancer in pregnancy: a literature review

    Arch Surg

    (2003)
  • M. Pilewskie et al.

    Association between recency of last pregnancy and biologic subtype of breast cancer

    Ann Surg Oncol

    (2012)
  • V.F. Borges et al.

    Pregnancy-associated breast cancer: an entity needing refinement of the definition

    Cancer

    (2012)
  • Screening for breast cancer: U.S. Preventive Services Task Force recommendation statement

    Ann Intern Med

    (2009)
  • B.Y. Ahn et al.

    Pregnancy- and lactation-associated breast cancer: mammographic and sonographic findings

    J Ultrasound Med

    (2003)
  • N.A. Pavlidis

    Coexistence of pregnancy and malignancy

    Oncologist

    (2002)
  • J.R. Daling et al.

    The relation of reproductive factors to mortality from breast cancer

    Cancer Epidemiol Biomarkers Prev

    (2002)
  • L.P. Middleton et al.

    Breast carcinoma in pregnant women: assessment of clinicopathologic and immunohistochemical features

    Cancer

    (2003)
  • C.G. Murphy et al.

    Current or recent pregnancy is associated with adverse pathologic features but not impaired survival in early breast cancer

    Cancer

    (2012)
  • A.L. Johansson et al.

    Increased mortality in women with breast cancer detected during pregnancy and different periods postpartum

    Cancer Epidemiol Biomarkers Prev

    (2011)
  • E.B. Callihan et al.

    Postpartum diagnosis demonstrates a high risk for metastasis and merits an expanded definition of pregnancy-associated breast cancer

    Breast Cancer Res Treat

    (2013)
  • T.M. Andersson et al.

    Increasing incidence of pregnancy-associated breast cancer in Sweden

    Obstet Gynecol

    (2009)
  • H.A. Abenhaim et al.

    Incidence, risk factors, and obstetrical outcomes of women with breast cancer in pregnancy

    Breast J

    (2012)
  • Y. Lee et al.

    Incidence and outcomes of pregnancy-associated cancer in Australia, 1994-2008: a population-based linkage study

    BJOG

    (2012)
  • S. Loibl et al.

    Breast carcinoma during pregnancy. International recommendations from an expert meeting

    Cancer

    (2006)
  • I. Hassan et al.

    Breast cancer during pregnancy and lactation in Zaria, Nigeria

    East Afr Med J

    (1995)
  • D. Huo et al.

    Parity and breastfeeding are protective against breast cancer in Nigerian women

    Br J Cancer

    (2008)
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