Cervical cancer risk and use of depot-medroxyprogesterone acetate in Costa Rica

Depot-medroxyprogesterone acetate injection (Depo-Provera): a highly effective contraceptive option with proven long-term safety

Depot-medroxyprogesterone acetate (Depo-Provera(R)) is a highly effective, nondaily hormonal contraceptive option that has been available in the United States for a decade, and worldwide for 40 years. Benefits and risks of hormonal therapy are often under scrutiny; however, long-term clinical experience has established the safety of this long-acting contraceptive. This article reviews the contraceptive efficacy, potential noncontraceptive health benefits and long-term safety of with regard to risk of cardiovascular events, breast and gynecologic malignancy and osteopenia. Comparisons with other hormonal contraceptives are made as clinically appropriate. Common patient management issues, including effects on menstrual cycle, body weight and mood, are also addressed. Finally, this review provides recommendations for appropriate patient selection.

Cervical cancer and use of hormonal contraceptives: a systematic review

BACKGROUND

Human papillomavirus (HPV) is believed to be the most important cause of cervical cancer. Recent studies suggest that long duration use of oral contraceptives increases the risk of cervical cancer in HPV positive women.

METHODS

Results from published studies were combined to examine the relationship between invasive and in situ cervical cancer and duration and recency of use of hormonal contraceptives, with particular attention to HPV infection.

FINDINGS

28 eligible studies were identified, together including 12531 women with cervical cancer. Compared with never users of oral contraceptives, the relative risks of cervical cancer increased with increasing duration of use: for durations of approximately less than 5 years, 5-9 years, and 10 or more years, respectively, the summary relative risks were 1.1 (95% CI 1.1-1.2), 1.6 (1.4-1.7), and 2.2 (1.9-2.4) for all women; and 0.9 (0.7-1.2), 1.3 (1.0-1.9), and 2.5 (1.6-3.9) for HPV positive women. The results were broadly similar for invasive and in situ cervical cancers, for squamous cell and adenocarcinoma, and in studies that adjusted for HPV status, number of sexual partners, cervical screening, smoking, or use of barrier contraceptives. The limited available data suggest that the relative risk of cervical cancer may decrease after use of oral contraceptives ceases. However, study designs varied and there was some heterogeneity between study results.

INTERPRETATION

Although long duration use of hormonal contraceptives is associated with an increased risk of cervical cancer, the public health implications of these findings depend largely on the extent to which the observed associations remain long after use of hormonal contraceptives has ceased, and this cannot be evaluated properly from published data.

Depot-medroxyprogesterone acetate (DMPA) and risk of invasive adenocarcinomas and adenosquamous carcinomas of the uterine cervix. WHO Collaborative Study of Neoplasia and Steroid Contraceptives

A hospital-based case-control study was conducted in two hospitals in Bangkok, Thailand, and in one hospital each in Chiang Mai, Thailand, Mexico City, Mexico and Nairobi, Kenya. One purpose of this study was to determine whether the long-acting progestational contraceptive, depot-medroxyprogesterone acetate (DMPA), alters risk of invasive cervical carcinomas with adenomatous histological features. Information on prior use of DMPA, screening for cervical cancer, and the suspected risk factors for this disease was ascertained from interviews of 239 women with adenocarcinomas and 85 women with adenosquamous carcinomas, as well of from a large pool of controls, 2534 of whom were matched to the cases included in this report. For selected subsets of these women, a smoking history was also elicited, blood specimens were collected for measurement of antibodies against herpes simplex and cytomegalovirus, and information on sexual behavior was obtained from interviews of their husbands. The relative risk (and 95% confidence interval) of adenomatous cervical carcinomas in women who ever used DMPA was estimated to be 0.75 (0.51, 1.11). No trends in risk were observed with duration of DMPA use, times since first or last use, or age at first use. The results provide reassurance that use of DMPA for over four years does not enhance risk of adenomatous cervical carcinomas, and risk is not increased after a potential latent period of over 12 years since initial exposure.

Cervical carcinoma in situ and use of depot-medroxyprogesterone acetate (DMPA). WHO Collaborative Study of Neoplasia and Steroid Contraceptives

The relationship of depot-medroxyprogesterone acetate (D-MPA) use to risk of cervical carcinoma in situ was investigated using data from a large multi-national, hospital-based case-control study. To avoid possible detection bias from Pap smear screening, final analyses were restricted to a subset of cases with symptoms at the time of their diagnosis of cervical carcinoma in situ. Relative to nonusers, the risk was elevated in women who had ever used DMPA and increased with duration of use. Decreasing trends in relative risk with times since first and last uses were observed in long-term users. Results from another portion of this same study did not show a relationship of invasive cervical cancer to DMPA use. These findings suggested that if DMPA increases the risk of cervical carcinoma in situ then either this is a reversible effect, or the cervical lesions induced by DMPA tend not to progress to invasive disease.

Depot-medroxyprogesterone acetate, other injectable contraceptives, and cervical neoplasia

The relationship between depot-medroxyprogesterone acetate (DMPA), and other injectable contraceptives and cervical neoplasia was reviewed mainly on the basis of three studies: the WHO Collaborative Study of Neoplasia and Steroid Hormone Contraceptives (2,009 cases and 9,583 controls collected in several, mainly developing, countries); a study of 369 cases of carcinoma in situ, 133 of invasive cancer and 646 controls collected by the National Tumor Registry of Costa Rica; and a cooperative study of 759 cases of invasive cervical cancer and 1,430 controls from four countries in Latin America (Costa Rica, Peru, Mexico and Colombia). There was no evidence of an appreciably elevated risk since most relative risks for ever users ranged from between 0.8 and 1.4, nor of consistent duration-risk relationship which was observed only in one study. The relative risk estimates for longest duration of use ranged from between 0.9 and 2.4. The data are still compatible with the absence of a causal association and with a moderately increased risk (up to a factor 1.5), which finds some biological plausibility as it is in agreement with the overall evidence of the relation between oral contraceptives and cervical neoplasia.

Modulatory influence of injectable contraceptive steroid medroxyprogesterone acetate on methylcholanthrene-induced carcinogenesis in the uterine cervix of mouse

Methylcholanthrene (approximately 300 micrograms) plus beeswax-impregnated thread, when placed inside the canal of the uterine cervix of virgin female adult mice for 30, 60 and 90 days produced cervical tumors in 0.0, 10 and 30% of mice, respectively. Employing this experimental cervical carcinogenesis model system, the present study evaluated the modulatory influence of medroxyprogesterone acetate (MPA) on the incidences of precancerous and cancerous lesions in the cervical epithelium as well as on phase I and phase II drug metabolizing enzymes and acid soluble sulfhydryl level in the liver. Intramuscular administration of MPA (50 micrograms every 5th day) to the carcinogen-thread inserted mice for 30, 60 and 90 days produced cervical tumors respectively in 0.0, 13.3 and 60.5% (P less than 0.05) of mice. A significant increase (P less than 0.05) in hyperplasia was also observed in the present study. A significant decrease in cytochrome b5 was found after 30 days.

Injectable contraceptives and risk of invasive cervical cancer: evidence of an association

In a case-control study conducted in Latin America, the relationship of injectable contraceptive (IC) use to risk of invasive cervical cancer was analyzed while controlling for a variety of other risk factors, including female and spouse sexual behavior and infection with human papillomaviruses (HPV). Thirty-two cases and 82 controls reported ever having used IC. Women reporting use of IC for less than 5 years had an adjusted RR of 0.5 (95% Cl = 0.3-0.9), but users for 5 or more years had an RR of 2.4 (95% Cl = 1.0-5.7). The effect of prolonged IC use was stronger for women reporting first use 10 or more years before interview (adjusted RR = 3.4, 95% Cl = 1.1-24.9) and more than 5 years since last use (adjusted RR = 5.3, 95% Cl = 1.1-10.0). Cervical cancer risk associated with prolonged IC use was particularly high among women who reported never having had a Pap smear or having had one 2 or more years before interview (adjusted RR = 6.3, 95% Cl = 2.1-18.7). The reduced cervical cancer risk associated with short-term use of IC may reflect intensive Pap smear screening as the method is initiated. Although hampered by small numbers, these results suggest an adverse effect of prolonged IC use on cervical cancer risk, particularly among women who cease participation in screening programs after terminating usage, and indicate that long-term IC users should be monitored for cervical disease until more conclusive results are available.

Seroepidemiology of chlamydia in Costa Rica

A population-based study of the sero-epidemiology of chlamydia was performed among a nationally representative sample of 760 Costa Rican women aged 25 to 59 years. Interviews and sera collection were completed between September 1984 and February 1985. The overall seroprevalence of chlamydial antibodies among these women was 56.1%. Women 25 to 39 years of age had a seroprevalence of 51.1%, while women 40 to 59 years of age had a seroprevalence of 64.2%. Women who reported no prior sexual activity had a seroprevalence rate of 48.6%, compared with a seroprevalence rate of 80.7% among women who reported three or more lifetime sexual partners. The geometric mean titre (GMT) of seropositive women ranged from 34.4 among the women who reported no prior sexual activity to 155.0 among the women with three or more lifetime sexual partners. Sero-positivity was more consistently associated with sexual activity than with age. Women with serological evidence of past Herpes simplex virus type 2 (HSV-2) or syphilis infection were more likely to be seropositive than were women without evidence of exposure to these sexually transmitted diseases, even when controlled for age and the number of lifetime sexual partners. The seropositivity among never sexually active women indicates the probable presence of Chlamydia pneumoniae infections, while the high seroprevalence of chlamydial antibodies among the sexually active women suggests that sexually transmitted Chlamydia trachomatis infections represent a public health problem not previously quantified in Costa Rica. Further seroepidemiological and/or culture studies are warranted to determine the incidence and prevalence of sexually transmitted chlamydial infection among men and younger women.