Benign ovarian cysts and ovarian cancer: a cohort study with implications for screening.
BACKGROUND
Whether some benign ovarian cysts can develop into cancerous cysts is not known. If a large proportion of ovarian cancers arose in this way, it might be possible to remove the benign cysts in a screening programme before they became malignant. We used follow-up data from a cohort of 5479 self-referred women without symptoms, who participated in a ultrasonographic-screening trial for early ovarian cancer between June, 1981, and August, 1987. We assessed whether the removal of persistent ovarian cysts from these women was associated with a reduction in the expected number of deaths from ovarian cancer in the cohort as a whole.


METHODS
The expected number of deaths from all causes, all cancers, and ovarian, breast, and colorectal cancers were calculated for the study cohort by the standard life-table method. The actual number of deaths and each cause were obtained and the proportional mortality ratio was calculated for each cause of death.


RESULTS
5135 (95%) of the participants in the original trial were traced. During the screening, five of these women were found to have stage I epithelial ovarian cancer and 88 had benign epithelial ovarian tumours. The number of reported deaths from all causes (387 [50% of expected]), all cancers (221 [71%]), and ovarian cancer (22 [90%]) was lower than expected because of the "healthy-volunteer effect". Proportional mortality ratios were 100% (by definition) for all cancers, 141% for breast cancer, 128% for ovarian cancer (95% CI 87.7-187.6, p=0.19), 84% for colorectal cancer, and 48% for lung cancer.


CONCLUSIONS
The removal of persistent ovarian cysts was not associated with a decrease in the proportion of expected deaths from ovarian cancer relative to other cancers during follow-up. For population-based screening of healthy women without a family history of ovarian cancer, a screening test is required that is specific and sensitive to early malignant disease, and inexpensive.
Crayford
T J
TJ
Department of Epidemiology and Public Health, Guy's, King's, and St Thomas' School of Medicine, King's College Hospital, London, UK. tim@crayford.net
Campbell
S
S
Bourne
T H
TH
Rawson
H J
HJ
Collins
W P
WP
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002423:Cause of Death; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008403:Mass Screening; D008875:Middle Aged; D010048:Ovarian Cysts / Q000000981:diagnostic imaging* / Q000401:mortality / Q000601:surgery; D010051:Ovarian Neoplasms / Q000000981:diagnostic imaging* / Q000401:mortality / Q000601:surgery; D011230:Precancerous Conditions / Q000000981:diagnostic imaging* / Q000401:mortality / Q000601:surgery; D011237:Predictive Value of Tests; D012307:Risk Factors; D015996:Survival Rate; D014463:Ultrasonography