Ovarian cancer begins in the fallopian tubes six-and-a-half years before it turns into the ‘silent killer’, according to a new study.
Scientists have mapped out its ‘evolutionary tree’, offering the hope of detecting it before it spreads, and ovarian tumors have been traced to their site of origin in the fallopian tubes for the first time.
The report suggests the genomic roots of most cases start in the fibrous tissue that connects the ovaries to the womb.
The new discovery by the Johns Hopkins researchers who worked on the report sheds light on the cause of the disease and paves the way for the development of new ways of preventing and treating it.
This diagram shows how ovarian cancer begins in the fallopian tubes and spreads to different parts of the body
About 20,000 women in the US are diagnosed with ovarian cancer each year. In 2014, the most recent year the CDC has collected data on, 14,195 women were killed by ovarian cancer.
Study leader Dr Victor Velculescu said: ‘Ovarian cancer treatments have not changed much in many decades.
‘This may be in part because we have been studying the wrong tissue of origin for these cancers.
‘If studies in larger groups of women confirm our finding that the fallopian tubes are the site of origin of most ovarian cancer then this could result in a major change in the way we manage this disease for patients at risk.’
Survival rates for ovarian cancer low, and only a third of patients with the illness live beyond 10 years.
The disease is often diagnosed late because symptoms only occur after it has already spread to other organs.
Many women with ovarian cancer suffer from vague discomfort, and some have been misdiagnosed with irritable bowel syndrome after reporting their symptoms. The illness also mimics the start of menopause.
EXPLAINED: OVARIAN CANCER
There are three types of tumors that can result in ovarian cancer.
Epithelial tumors: About 90 percent of ovarian cancer cases stem from these tumors, which originate in the tissue that covers the outside of the ovaries.
Stromal tumors: These account for about seven percent of ovarian tumors. They are found in the tissue that contains cells that produce hormones and are usually detected earlier than the other two types of tumors.
Germ cell tumors: These originate in egg-producing cells and, while rare, tend to be found in younger women.
Symptoms of ovarian cancer:
- abdominal bloating
- abdominal swelling
- weight loss
- discomfort in the pelvic area
- needing to urinate frequently
Some scientists have suspected that the most common form of ovarian cancer originates in the fallopian tubes.
Now, an analysis of nine patients has created the illness’s ‘evolutionary tree’, confirming that ovarian cancers do begin in the fallopian tubes.
Researchers found that STICs (serous tubal intraepithelial carcinomas), which begin in the fallopian tubes, lead to the development of cancer in the ovaries after a ‘seeding event’ in the fallopian tubes.
They also concluded that this process took an average of six-and-a-half years among the participants.
But once the cancers reached their ovaries the progression of the disease was estimated to have occurred within two years.
Dr Velculescu said: ‘This aligns with what we see in the clinic, that newly-diagnosed ovarian cancer patients most often already have widespread disease.’
He said bigger studies are required to validate the new findings before there can be a change in clinical practice.
There are already ongoing trials involving the removal of fallopian tubes instead of ovaries in women with the cancer-causing BRCA1 and BRCA2 gene mutations.
But Dr Velculescu also said the ‘fallopian-first’ theory may not apply to other, less common types of the disease.
However, confirmation of their work may help spare some women the removal of their ovaries and the loss of hormones that leads to increased risk of heart disease and other illnesses.
Dr Velculescu said: ‘The window of time that exists between the development of a STIC lesion and metastatic disease highlights the importance of new screening approaches such as blood sample methods for early detection of ovarian cancer.’
Ovarian cancer is the fifth deadliest cancer among women and is generally diagnosed too late.
The study published by Nature Communications examined cell samples collected from various locations in the nine women – five of whom had the most common form called high grade serous ovarian carcinoma.
Samples from STIC lesions and normal cells were also collected from four women who had their ovaries and fallopian tubes removed because of hereditary gene mutations or in once case a pelvic growth.