Limits...
Injectable and oral contraceptive use and cancers of the breast, cervix, ovary, and endometrium in black South African women: case-control study.

Urban M, Banks E, Egger S, Canfell K, O'Connell D, Beral V, Sitas F - PLoS Med. (2012)

Bottom Line: Evidence regarding the relationship between injectable contraceptives and these cancers is limited, especially in black South Africans, among whom injectable contraceptives are used more commonly than oral contraceptives.For current and more recent users versus never users of oral or injectable contraceptives, the odds ratios (ORs) for breast cancer were significantly increased in users of oral and/or injectable contraceptives (OR 1.66, 95% CI 1.28-2.16, p<0.001) and separately among those exclusively using oral (1.57, 1.03-2.40, p = 0.04) and exclusively using injectable (OR 1.83, 1.31-2.55, p<0.001) contraceptives; corresponding ORs for cervical cancer were 1.38 (1.08-1.77, p = 0.01), 1.01 (0.66-1.56, p = 0.96), and 1.58 (1.16-2.15, p = 0.004).There was no significant increase in breast or cervical cancer risk among women ceasing hormonal contraceptive use ≥10 y previously (p = 0.3 and p = 0.9, respectively).

View Article: PubMed Central - PubMed

Affiliation: NHLS/MRC Cancer Epidemiology Research Group, National Health Laboratory Services, Johannesburg, South Africa. margaret.urban@nhls.ac.za

ABSTRACT

Background: Oral contraceptives are known to influence the risk of cancers of the female reproductive system. Evidence regarding the relationship between injectable contraceptives and these cancers is limited, especially in black South Africans, among whom injectable contraceptives are used more commonly than oral contraceptives.

Methods and findings: We analysed data from a South African hospital-based case-control study of black females aged 18-79 y, comparing self-reported contraceptive use in patients with breast (n = 1,664), cervical (n = 2,182), ovarian (n = 182), and endometrial (n = 182) cancer, with self-reported contraceptive use in 1,492 control patients diagnosed with cancers with no known relationship to hormonal contraceptive use. We adjusted for potential confounding factors, including age, calendar year of diagnosis, education, smoking, alcohol, parity/age at first birth, and number of sexual partners. Among controls, 26% had used injectable and 20% had used oral contraceptives. For current and more recent users versus never users of oral or injectable contraceptives, the odds ratios (ORs) for breast cancer were significantly increased in users of oral and/or injectable contraceptives (OR 1.66, 95% CI 1.28-2.16, p<0.001) and separately among those exclusively using oral (1.57, 1.03-2.40, p = 0.04) and exclusively using injectable (OR 1.83, 1.31-2.55, p<0.001) contraceptives; corresponding ORs for cervical cancer were 1.38 (1.08-1.77, p = 0.01), 1.01 (0.66-1.56, p = 0.96), and 1.58 (1.16-2.15, p = 0.004). There was no significant increase in breast or cervical cancer risk among women ceasing hormonal contraceptive use ≥10 y previously (p = 0.3 and p = 0.9, respectively). For durations of use ≥5 y versus never use, the ORs of ovarian cancer were 0.60 (0.36-0.99, p = 0.04) for oral and/or injectable contraceptive use and 0.07 (0.01-0.49, p = 0.008) for injectable use exclusively; corresponding ORs for endometrial cancer were 0.44 (0.22-0.86, p = 0.02) and 0.36 (0.11-1.26, p = 0.1).

Conclusions: In this study, use of oral and of injectable hormonal contraceptives was associated with a transiently increased risk of breast and cervical cancer and, for long durations of use, with a reduced risk of ovarian and endometrial cancer. The observed effects of injectable and of oral contraceptives on cancer risk in this study did not appear to differ substantially.

Show MeSH

Related in: MedlinePlus

Odds ratio for ovarian and endometrial cancer in relation to use of hormonal contraceptives, according to duration of use.Adjusted OR (95% CI) for (A) ovarian cancer and (B) endometrial cancer in relation to use of oral and injectable contraceptives, adjusted for age at diagnosis, year of diagnosis, education, tobacco smoking, alcohol consumption, parity/age at first birth, number of sexual partners, urban/rural residence, and province of birth. Squares represent ORs, and horizontal lines indicate 95% CI. Diamonds represent the ORs and confidence intervals for the group comprising women from all three exposure categories immediately above.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3295825&req=5

pmed-1001182-g002: Odds ratio for ovarian and endometrial cancer in relation to use of hormonal contraceptives, according to duration of use.Adjusted OR (95% CI) for (A) ovarian cancer and (B) endometrial cancer in relation to use of oral and injectable contraceptives, adjusted for age at diagnosis, year of diagnosis, education, tobacco smoking, alcohol consumption, parity/age at first birth, number of sexual partners, urban/rural residence, and province of birth. Squares represent ORs, and horizontal lines indicate 95% CI. Diamonds represent the ORs and confidence intervals for the group comprising women from all three exposure categories immediately above.

Mentions: The risk of ovarian cancer did not differ significantly between women who had never used hormonal contraceptives and those who had used oral and/or injectable contraceptives for a total of less than 5 y (OR 0.69, 0.39–1.21, p = 0.2) (Figure 2A). For those using hormonal contraceptives for a total of ≥5 y, the risk of ovarian cancer was significantly reduced (OR 0.60, 0.36–0.99, p = 0.04) (Figure 2A) compared to never users, but there was no significant difference in the overall risk of ovarian cancer by duration of use (p = 0.7) or by time since last use (p = 0.97) for oral and/or injectable contraceptives (Table 4). The sample sizes are too small for reliable comparisons by type of contraceptive used; however, significant reductions in ovarian cancer risk were observed in ever users (OR 0.35, 0.17–0.71, p = 0.004) (Table 2) and long-duration users of injectable contraceptives exclusively (OR 0.07, 0.01–0.49, p = 0.008, based on one exposed case), compared with never users of hormonal contraceptives (Figure 2A).


Injectable and oral contraceptive use and cancers of the breast, cervix, ovary, and endometrium in black South African women: case-control study.

Urban M, Banks E, Egger S, Canfell K, O'Connell D, Beral V, Sitas F - PLoS Med. (2012)

Odds ratio for ovarian and endometrial cancer in relation to use of hormonal contraceptives, according to duration of use.Adjusted OR (95% CI) for (A) ovarian cancer and (B) endometrial cancer in relation to use of oral and injectable contraceptives, adjusted for age at diagnosis, year of diagnosis, education, tobacco smoking, alcohol consumption, parity/age at first birth, number of sexual partners, urban/rural residence, and province of birth. Squares represent ORs, and horizontal lines indicate 95% CI. Diamonds represent the ORs and confidence intervals for the group comprising women from all three exposure categories immediately above.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3295825&req=5

pmed-1001182-g002: Odds ratio for ovarian and endometrial cancer in relation to use of hormonal contraceptives, according to duration of use.Adjusted OR (95% CI) for (A) ovarian cancer and (B) endometrial cancer in relation to use of oral and injectable contraceptives, adjusted for age at diagnosis, year of diagnosis, education, tobacco smoking, alcohol consumption, parity/age at first birth, number of sexual partners, urban/rural residence, and province of birth. Squares represent ORs, and horizontal lines indicate 95% CI. Diamonds represent the ORs and confidence intervals for the group comprising women from all three exposure categories immediately above.
Mentions: The risk of ovarian cancer did not differ significantly between women who had never used hormonal contraceptives and those who had used oral and/or injectable contraceptives for a total of less than 5 y (OR 0.69, 0.39–1.21, p = 0.2) (Figure 2A). For those using hormonal contraceptives for a total of ≥5 y, the risk of ovarian cancer was significantly reduced (OR 0.60, 0.36–0.99, p = 0.04) (Figure 2A) compared to never users, but there was no significant difference in the overall risk of ovarian cancer by duration of use (p = 0.7) or by time since last use (p = 0.97) for oral and/or injectable contraceptives (Table 4). The sample sizes are too small for reliable comparisons by type of contraceptive used; however, significant reductions in ovarian cancer risk were observed in ever users (OR 0.35, 0.17–0.71, p = 0.004) (Table 2) and long-duration users of injectable contraceptives exclusively (OR 0.07, 0.01–0.49, p = 0.008, based on one exposed case), compared with never users of hormonal contraceptives (Figure 2A).

Bottom Line: Evidence regarding the relationship between injectable contraceptives and these cancers is limited, especially in black South Africans, among whom injectable contraceptives are used more commonly than oral contraceptives.For current and more recent users versus never users of oral or injectable contraceptives, the odds ratios (ORs) for breast cancer were significantly increased in users of oral and/or injectable contraceptives (OR 1.66, 95% CI 1.28-2.16, p<0.001) and separately among those exclusively using oral (1.57, 1.03-2.40, p = 0.04) and exclusively using injectable (OR 1.83, 1.31-2.55, p<0.001) contraceptives; corresponding ORs for cervical cancer were 1.38 (1.08-1.77, p = 0.01), 1.01 (0.66-1.56, p = 0.96), and 1.58 (1.16-2.15, p = 0.004).There was no significant increase in breast or cervical cancer risk among women ceasing hormonal contraceptive use ≥10 y previously (p = 0.3 and p = 0.9, respectively).

View Article: PubMed Central - PubMed

Affiliation: NHLS/MRC Cancer Epidemiology Research Group, National Health Laboratory Services, Johannesburg, South Africa. margaret.urban@nhls.ac.za

ABSTRACT

Background: Oral contraceptives are known to influence the risk of cancers of the female reproductive system. Evidence regarding the relationship between injectable contraceptives and these cancers is limited, especially in black South Africans, among whom injectable contraceptives are used more commonly than oral contraceptives.

Methods and findings: We analysed data from a South African hospital-based case-control study of black females aged 18-79 y, comparing self-reported contraceptive use in patients with breast (n = 1,664), cervical (n = 2,182), ovarian (n = 182), and endometrial (n = 182) cancer, with self-reported contraceptive use in 1,492 control patients diagnosed with cancers with no known relationship to hormonal contraceptive use. We adjusted for potential confounding factors, including age, calendar year of diagnosis, education, smoking, alcohol, parity/age at first birth, and number of sexual partners. Among controls, 26% had used injectable and 20% had used oral contraceptives. For current and more recent users versus never users of oral or injectable contraceptives, the odds ratios (ORs) for breast cancer were significantly increased in users of oral and/or injectable contraceptives (OR 1.66, 95% CI 1.28-2.16, p<0.001) and separately among those exclusively using oral (1.57, 1.03-2.40, p = 0.04) and exclusively using injectable (OR 1.83, 1.31-2.55, p<0.001) contraceptives; corresponding ORs for cervical cancer were 1.38 (1.08-1.77, p = 0.01), 1.01 (0.66-1.56, p = 0.96), and 1.58 (1.16-2.15, p = 0.004). There was no significant increase in breast or cervical cancer risk among women ceasing hormonal contraceptive use ≥10 y previously (p = 0.3 and p = 0.9, respectively). For durations of use ≥5 y versus never use, the ORs of ovarian cancer were 0.60 (0.36-0.99, p = 0.04) for oral and/or injectable contraceptive use and 0.07 (0.01-0.49, p = 0.008) for injectable use exclusively; corresponding ORs for endometrial cancer were 0.44 (0.22-0.86, p = 0.02) and 0.36 (0.11-1.26, p = 0.1).

Conclusions: In this study, use of oral and of injectable hormonal contraceptives was associated with a transiently increased risk of breast and cervical cancer and, for long durations of use, with a reduced risk of ovarian and endometrial cancer. The observed effects of injectable and of oral contraceptives on cancer risk in this study did not appear to differ substantially.

Show MeSH
Related in: MedlinePlus