May/June, 1998 Volume XII Number 12




Black women and breast cancer

Breast cancer is the second leading cause of cancer death among African-American women" [189, p13]. "For the period of 1985-1989, the...incidence for each 5-year age group younger than 40 years was higher among black women than among white women" [300].
The incidence of breast cancer is increasing in both the black and white population, but young black women are getting more breast cancer and dying from it more often than young white women. Why? Researchers are well aware that two major risk factors have been more prevalent in young blacks than in whites, namely the incidence of early oral contraceptive use and having an abortion performed early in a woman's reproductive life (although these rates have increased for both groups since the 1960s).
White and Daling addressed this issue in 1987. They noted that young black women had almost double the rate of increased breast cancer incidence compared to the rest of the population when comparing incidence rates from the mid 1970s to the early 1980s. In discussing possible reasons for the increase they state: "Recently, two other factors have emerged as possible risk factors for breast cancer: oral contraceptive use before first pregnancy and abortion before first term pregnancy." [153, p242].
It would seem to be very reasonable to propose that these two risk factors are at least partly responsible for the marked increase in incidence and mortality of young black women compared to young white women over the past 15 years.

Q-11A What has happened to the incidence of breast cancer in young black and white women over the past 25 years?

Let's look at some of the data.

Figure 11A (constructed from data from the National Cancer Institute [317A]) shows us the incidence of breast cancer in both young black and white women, ages 20-44, from the block of years of 1975-9 as compared to the 1988-92.
Young white women experienced a 10.1% increase (ie, going from 36.6 to 40.3 breast cancer "cases" per 100,000 women in the 20-44 age group), while young black women experienced a 12.6% increase, going from a rate of 40.8 to 45.6 per 100,000 women.

Figure 11A:

RISING RATES OF BREAST CANCER
IN WHITE AND BLACK WOMEN




Q-11B What about the mortality rate in young white and black women?

Figure 11B [317, p124] shows the relative death rates per 100,000 women for women under age 50. The mortality rate of young white females fell from 6.7 (in 1975) to 5.9 (in 1990). Unfortunately, the rate for young black women actually rose from 7.9 in 1975 to 8.9 in 1990. So from 1975 to 1990, while breast cancer mortality decreased in white women by about 9%, it increased in young black women by over 12%.

Figure 11B:

MORTALITY FROM BREAST CANCER IN WHITE AND BLACK WOMEN




Q-11C In accordance with this finding, if the hypothesis is correct, we would expect young black women to have a higher incidence of abortions performed early in a woman's reproductive life and/or a history of early OCP (oral contraceptive pill) use. Does the historical data support this?

Absolutely. Table 11A shows the abortion rates for both black and white women for different age groups. Data on the abortion rate in young black women became available in 1981, and the rates of abortion for this period as well as for the 1990-91 period are shown.

Table 11A:

ABORTION RATES IN YOUNG WHITE AND BLACK WOMEN*

* Sources: 70 and 74 (rates in abortions per 1,000 women)
** The data for women under age 15 in the 1990-91 years was computed on a different scale than the rates for the under age 15 women in 1981.

What do the data show us? Young black women obviously had a higher rate of abortions performed early in a woman's reproductive life than young white women. Although few statistics are available from the 1970s, it is highly probable that this trend was also true for the 1970s. One can also see that very young blacks (ie, those under 15) have an especially high relative rate of abortion compared to young whites__specifically they have more than five times the abortion rate at this age, for both the 1981 and the 1990-91 time periods.


Q-11D Young black women also have more early live births than young white women, does this not protect them from breast cancer?

It is true that young black women have about twice as many live births per 1,000 women than young white women, but those who have a live birth, in any given year, are almost always different women than those who had an induced abortion that year. Young black women have a higher abortion rate as well as a higher birth rate than young white women. It is also likely that many women who had an abortion performed early in their reproductive life, especially those under age 15 and many of those aged 15-17, will be choosing to abort their first child. These young women would be at an especially high risk, since the risk of having an abortion before a full term birth in young women has been noted to carry a 150% increased risk according to at least one large study [103].


Q-11E What do the records show concerning early OCP (oral contraceptive pill) use among young white and black women?

Table 11B:

PERCENT OF WOMEN AGE 15-19 USING ORAL CONTRACEPTIVES*

* Sources [75, 79, 80A]
** The 1976 data is based upon the category of: "Percentage of women aged 15-19 who ever used a contraceptive method, by first method used." [75]

It is clear that young black women have had a higher rate of early OCP use than young white women. This trend has continued from the mid-1970s through at least the early 1990s and is even noted in the very young women aged 15-17 according to the cited data from 1982. The early use of OCPs by young women, especially young black women, could certainly account for part of the increase in breast cancer in young black women. It should also be noted that many young black and white women have used OCPs either before a first-live birth or after an induced abortion, making them especially vulnerable since they would now have two risk factors. We must remember that early OCP use, especially when used before a woman has ever had a child increases the risk of breast cancer. In 1990, Romieu et al's meta-analysis showed women under age 45 who had taken OCPs for four or more years prior to their first term pregnancy had a 72% increased of breast cancer [{RR=1.72 (1.36-2.19)} [55]


Q-11F Do women who have abortions really have a higher rate of OCP use?

It would appear so. Campbell et al noted that: "Our findings on adolescents support those of several authors who cited that adolescent women were more likely to use contraceptives after abortion" [185A, p819].


Q-11G Have any researchers commented upon the probable connection between early OCPs, abortion and breast cancer when taken/performed in young women?

Yes. It was already noted that White et al hypothesized that oral contraceptive use before a first pregnancy and abortion before first term pregnancy could be risk factors. [153, p242]. Kelsey (1993) also noted that "below age 45, the higher rates (of breast cancer) in blacks than in whites in recent years have been hypothesized to reflect more frequent abortion and use of oral contraceptives among young women" [115, p14]. Lastly, Mayberry et al [49] noted that "..the higher breast cancer incidence rate among young black women may be explained by a higher prevalence and duration of oral contraceptive use" [49, p1454].


Q-11H What have the specific studies of the oral contraceptive pill and breast cancer shown in young black women?

Several authors have performed research specifically in black women who have breast cancer as noted in table 11C.

Table 11C:

BLACK WOMEN AND RISK OF NON-SPECIFIC OCP USE


Table 11C presents a number of specific studies regarding OCP use and young blacks. The noted results should certainly be taken seriously, especially since each of then is statistically significant. Although none of the studies specifically examined OCP use prior to FTP, these studies certainly serve as a warning that early OCP could carry at least as much risk as those presented in Table 11C.


Q-11I What about the risks of abortion in young black women?

Mayberry [14] noted an odds ratio of 1.1 (0.5-2.3) for one induced abortion and 1.4 (0.5-3.8) for two or more abortions in women aged 20-39. Laing [119] noted a 50% increased trend [RR= 1.5 (0.7-3.5)] in women under age 40, a 180% increase [RR=2.8 (1.0-8.1)] in women aged 41-49 and a 370% increase [RR= 4.7 (2.6-8.4)] in women over age 50, who had ever had an abortion. In a later study [120] she noted a 144% increase (RR = 2.44) in a comparison of sisters, one of whom had an abortion performed early in her reproductive life. Although this author found no study which specifically examined the effect of abortion prior to first term pregnancy in young black women, Mayberry and Laing's work certainly serve to warn that abortion performed early in a woman's life is likely to carry significant risk.


Q-11J Do black women have "worse" breast cancer than white women?

Yes, black women generally have more aggressive breast cancer and have shorter survival times than white women. Eley et al [188, p953] estimated that when comparing white and black women who had breast cancer, black women had between a 70-90% increased risk of dying from breast cancer than white women, independent of the stage in which the cancer was diagnosed. He also found that black women had a 2.3 fold risk (ie, a 130% increased risk) of having estrogen negative breast tumors. [In general, estrogen negative tumors respond more poorly to treatment than do estrogen positive tumors.] Some have argued that the difference in breast cancer mortality between black and white women is a reflection of the different standards of care of women who have different incomes.
Although this statement could certainly be true, it does not answer the question as to why in general, black women have more aggressive breast cancer than white women, nor does it answer the question of why breast cancer mortality rates are have risen faster in young black women than in young white women.


Q-11K Could the fact that Eley et al found that black women had more estrogen negative tumors be a result of their increased early OCP and abortion usage?

Yes, it is possible, but not proven. As noted earlier, Olsson et al [17B] found that women who took OCPs early in life developed a more aggressive type of breast cancer. The same phenomenon may certainly be occurring in black women who have a higher rate of estrogen negative tumors.


BIBLIOGRAPHY

1 Brinton LA, Daling JR et al. Oral contraceptives and breast cancer risk among younger women. JNCI. 6/7/1995; 87: 827-35.

14 Maybery RM. Age-specific patterns of association between breast cancer and risk factors in black women, ages 20 to 39 and 40 to 54. Ann. Epidemiol. 1994; 4: 205-213.

17B Olsson H, Borg A, et al. Early oral contraceptive use and premenopausal breast cancer-A review of studies performed in southern Sweden. Cancer Detection and Prevention. 1991; 15: 265-271.

18 Palmer J, Ros49 Mayberry RM, Stoddard-Wright C. Breast cancer risk factors among black women and white women: similarities and differences. American Journal of Epidemiology. 1992; 136: 1445-1456.

49 Mayberry RM, Stoddard-Wright C. Breast cancer risk factors among black women and white women: similarities and differences. American Journal of Epidemiology. 1992; 136: 1445-1456.

55 Romieu I, Berlin J, et al. Oral contraceptives and breast cancer. Review and meta-Analysis. Cancer. 1990; 66: 2253-2263.

70 Ventura S, Taffel S, et al. Trends in pregnancies and pregnancy rates, United States, 1980-1992. Monthly Vital Statistics Report. 1995; 43: 1-24.

74 Hayes CD. Risking the Future. Washington, D.C.: National Academy Press, 1987.

75 Zelnik M, Kantner J. Sexual activity, contraceptive use and pregnancy among metropolitan-area teenagers: 1971-1979. Family Planning Perspectives. 1980; 12: 230-237.

79 Bachrach C, Mosher W. Use of Contraception in the United States, 1982. Vital and Health Statistics of the National Center for Health Statistics [USDept. of Health and Human Services]. Dec. 4, 1984; Number 102: 1-8.

80A US Government statistics regarding OCP use in black and white women. Source cannot be officially cited until government publication is made public (work currently in progress).

103 Daling J, Malone K, et al. Risk of breast cancer among young women: relationship to induced abortion. JNCI. 1994; 86: 1584-1592.

115 Kelsey J, Horn-Ross P. Breast cancer: Magnitude of the problem and descriptive epidemiology. Epidemiologic Reviews:1993; 15: 7-16.

119 Laing AE, Demenais FM, et al. Breast cancer risk factors in African-American women: The Howard University tumor registry experience. Journal of National Medical Association. 1993; 85 (12): 931-939.

120 Laing AE, Bonney GE, et al. Reproductive and lifestyle factors for breast cancer in African-American women. Genet. Epi. 1994; A300.153 White E, Daling J, et al. Rising incidence of breast cancer among young women in Washington State. JNCI. 987; 79: 239-43.

185A Campbell NB, et al. Abortion in Adolescence. Adolescence. 1988; 23: 813-823.

188 Eley JW, Hill HA, et al. Racial differences in survival from breast cancer. JAMA. 1994; 272: 947-954.

189 Cancer fact and figures for African Americans. American Cancer Society. 1996.

300 Miller, BA et al., Cancer Statistics Review: 1973-1989. Bethesda MD: National Cancer Institute, 1992. NIH Publication Number 92-2289]

317 National Cancer Institute. SEER Cancer Statistics Review, 1973-1992: Tables and Graphs. Bethesda, Maryland.

317A SEER Data. Incidence rates of breast cancer in Black and White women age 20-44


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