The impact of ovulation on fallopian tube epithelial cells: evaluating three hypotheses connecting ovulation and serous ovarian cancer

Reproductive factors in relation to ovarian cancer: a case-control study in Northern Vietnam

BACKGROUND

Ovarian cancer, one of the most common cancers in women and the most serious gynecologic cancer, is known to be influenced by reproductive factors, but these factors have not previously been examined in Vietnamese women.

STUDY DESIGN

We analyzed 262 ovarian cancer patients recruited from 27 hospitals in 12 provinces and Ha Noi City from April 2001 to May 2006, plus 755 controls matched by age and residential address.

RESULTS

The risk of ovarian cancer was significantly lower in parous women than nulliparous women. Use of an intrauterine contraceptive device was also associated with a reduced risk. In contrast, induced abortion, late menopause and years of ovulation were significantly associated with an increased risk of cancer.

CONCLUSIONS

Parity and intrauterine device use were associated with a reduced risk of ovarian cancer in Vietnamese women, whereas induced abortion, late menopause and years of ovulation were associated with an increased risk.

High-grade serous ovarian cancer arises from fallopian tube in a mouse model

Although ovarian cancer is the most lethal gynecologic malignancy in women, little is known about how the cancer initiates and metastasizes. In the last decade, new evidence has challenged the dogma that the ovary is the main source of this cancer. The fallopian tube has been proposed instead as the primary origin of high-grade serous ovarian cancer, the subtype causing 70% of ovarian cancer deaths. By conditionally deleting Dicer, an essential gene for microRNA synthesis, and Pten, a key negative regulator of the PI3K pathway, we show that high-grade serous carcinomas arise from the fallopian tube in mice. In these Dicer-Pten double-knockout mice, primary fallopian tube tumors spread to engulf the ovary and then aggressively metastasize throughout the abdominal cavity, causing ascites and killing 100% of the mice by 13 mo. Besides the clinical resemblance to human serous cancers, these fallopian tube cancers highly express genes that are known to be up-regulated in human serous ovarian cancers, also demonstrating molecular similarities. Although ovariectomized mice continue to develop high-grade serous cancers, removal of the fallopian tube at an early age prevents cancer formation--confirming the fallopian tube origin of the cancer. Intriguingly, the primary carcinomas are first observed in the stroma of the fallopian tube, suggesting that these epithelial cancers have a mesenchymal origin. Thus, this mouse model demonstrates a paradigm for the origin and initiation of high-grade serous ovarian carcinomas, the most common and deadliest ovarian cancer.