Both uterine and ovarian cancers target the female reproductive system. Other than that, they are worlds apart.
The incidence of uterine or womb cancer has been rising rapidly. In 1998, it was the 10th most common women's cancer. Now it ranks fourth, with more than 400 women diagnosed each year.
Still, Dr Tay Eng Hseon, medical director of the Thomson Women Cancer Centre, called it a "happy" cancer as most patients are diagnosed early and the cure rate is high.
This is because the symptoms are obvious: it causes unusual bleeding in the early stages, and most women would see a doctor, have it diagnosed and treated before the cancer spreads beyond the uterus.
But ovarian cancer is the deadliest of all gynaecological cancers, he said. There are no symptoms in the early stages, so the majority of those hit find out only at a late stage.
It is the fifth most common cancer among women, affecting about 350 a year.
The survival rate is good for those who discover it early, usually as a result of regular gynaecological checks.
Doctors say one of the reasons ovarian cancer is on the rise is the trend of women having fewer children, and later in life.
"Developed countries tend to have a higher prevalence, because more women work, and so they have fewer children, and later in life," said Dr Chia Yin Nin, a gynaecology-oncologist at Gleneagles Hospital.
Dr John Chia of the National Cancer Centre Singapore said having more children protects women against ovarian cancer, as the risk is lowered when women ovulate less. They do not ovulate when pregnant.
He said: "When eggs are released, they rupture through the fallopian tubes, and that leads to some damage. So every time women ovulate, it opens the door to cancer cells and carcinogens."
Going on the pill also confers protection against ovarian cancer, said Dr Tay. In fact, just going on the pill for five cumulative years cuts the risk of getting this cancer by half.
The best thing a woman can do to prevent ovarian cancer is to "have two children, breastfeed, then go on the pill till the age of 45", he said.
This is because there is no ovulation during pregnancy, breastfeeding and when women are on the pill, so it gives the ovaries a rest. But the pill is not recommended for older women as they could be at risk of getting deep vein thrombosis.
There are various types of ovarian cancers, with epithelial, in which the cancer forms on the surface of the ovaries, being the most common and also the most serious. About four in five ovarian cancers are this type.
Even after surgery and chemotherapy, the majority of patients face a relapse 12-20 months later.
Dr Tay said that knowing this, doctors are recommending maintenance therapy, which means treating the cancer like a chronic disease that needs to be suppressed.
Patients are given Avastin every three weeks, typically a 90-minute intravenous infusion of the drug, which slows the growth of new blood vessels and thus the development of tumours.
The results of a trial on this, presented in May at the American Society of Clinical Oncology, one of the world's biggest cancer meetings, show that it reduced the risk of disease progression by 29 per cent.
Dr Tay said this drug is well tolerated, and "the physical toxicity is less than the financial toxicity" as it costs $3,000-$5,000 per treatment, depending on the person's weight.
The recommendation is for 12 treatments. But this can be extended for up to two years - to keep cancer cells at bay for longer - if the drug continues to remain effective in preventing blood-vessel growth.
Another form of ovarian cancer is germ cell, which is aggressive and usually hits women in their teens and early 20s.
The safest option is to remove the ovaries, but many of the women are still at a child-bearing age so Dr Tay tries to preserve the ovaries if they ask him to, saying: "It's a crime to remove their ovaries. The cancer does not affect their fertility and it does not transmit to their babies."
Finally, there is borderline ovarian cancer, technically a cancer since the cells proliferate but, unlike other cancers, it does not destroy other tissue, said Dr Tay.
Typically, doctors do a frozen section - send a piece of the tumour taken during surgery to the pathologist for immediate analysis. The results can come in while the patient is still in the operating theatre.
If it is borderline cancer, then only the growth is removed. If it is unclear whether the patient has borderline cancer and she is young, the surgeon would be conservative and preserve her womb.
For older patients no longer planning a family, a hysterectomy to remove the reproductive organs would be the typical choice.
•Next week: Liver cancer
WHAT IT SHOULD HAVE BEEN: In yesterday's report, "Going on the pill 'can help protect' against ovarian cancer", a picture of Dr David Tan from the National University Cancer Institute, Singapore, was wrongly identified as Dr John Chia from the National Cancer Centre Singapore.
We are sorry for the error.