WOMEN 'S HEALTH AND MENOPAUSE : - National Heart, Lung ...

TABLE 11–3 (continued)
Thus, a strong association between HRT and invasive
or borderline malignant epithelial ovarian neoplasms
can be excluded, although relationships
with histological subtypes may exist. However, it
is possible that ovarian cancers in women who had
used HRT are more often classified as endometrioid
tumors, and there is a lack of clear understanding
of the biologic meaning of histologic type.
Very little information is available on the addition
of progestin to estrogen preparations. In a cohort of
4,544 women, recruited since 1978 from 21 menopause
clinics in Britain and followed to 1988, 55
HRT use could not be related to ovarian cancer risk
increase (RR = 0.63); similarly, in a multicenter
case-control study (N = 377 cases and 2,030 controls)
conducted between 1976 and 1985 in various
United States areas (Kaufman et al., 1989), 98 only
2 percent of cases and controls had ever used combination
HRT, and the multivariate RR was 0.7 (95
percent CI 0.2–1.8).
Thus, the evidence on HRT and ovarian cancer is less
consistent than that for endometrial and breast cancer,
but a moderate association remains open to debate.
234
Overviews
Reference
Whittemore et al., 105 1992,
U.S.A.
Harris et al., 106 1992,
U.S.A.
Study Design
Pooled analysis of
12 U.S. hospitalandpopulationbased
case-control
studies
As above
No. of Cases
(Age Group)
2,197
(all ages)
327
(all ages)
Relative Risks
for Ever HRT Use
0.9/1.1
0.9/1.1
5. COLORECTAL CANCER
Observations
Invasive cancers.
No duration-risk
relationship.
Borderline ovarian
neoplasms. Hospitalbased/population-based
studies. No duration-risk
relationship.
Colorectal cancer is the most frequent cancer in
nonsmokers of both sexes combined in Western
countries. 87,110 Similar incidences between the two
sexes are seen for colon cancer, while a male
predominance is found for rectal cancer.
During the last two decades, mortality rates from
colorectal cancer in many developed countries
have declined in women but not in men. 24,87 A role
of exogenous female hormones (i.e., OCs, and
HRT) on these trends is possible.
Eight cohort studies (see table 11–4) reported
information on HRT use and colorectal cancer risk,
for a total of over 2,400 cases. Most studies
showed RRs around or below unity. A significant
inverse relation was found in two cohort investigations,
including the largest one focusing on fatal
colon cancers (table 11–4). 56,90,111–119 Findings from a
recent study also suggested that HRT use may
improve short-term survival after a diagnosis of
colon cancer. 120