In comparison with cervical cancer, vulvar cancer is rare in Singapore. According to the National Cancer Registry for years 1998 – 2003, there were a total of 1033 cervical cancers whereas there were only 178 vulva cancers. KK Gynaecological Cancer Centre sees about 400 new cancer cases each year, however, vulvar cancer only accounts for 1.5% of the cases.

A retrospective review of our 47 vulvar cancers between 1995 to 2003 found that 92.7% were Chinese [(our Chinese population percentile is 76.5% (population statistics 2002)], 4.9% were Malays, while none were Indians.

43.2% of the vulvar cancers were associated with vulvar intraepithelial neoplasia 3 (VIN3), while 16.2% were associated with Lichen sclerosus (LS). Three quarters of the adenocarcinomas arose on a background of Paget’s Disease of the Vulvar. None of the patients were current smokers and only 3 were noted to have ever smoked.

The prevalence of Human Papillomavirus (HPV) in Singapore is evident by the fact that cervical cancer is common. HPV is also thought to play an etiological role in VIN and vulvar cancer. Our study showed that over 40% of our vulvar cancers were associated with VIN3. Nevertheless, vulvar cancer is uncommon in Singapore. Despite the prevalence of HPV in Singapore, it appears from the study that there may be other factors in our population protecting against the development of vulvar cancer.

Only 4% of women in Singapore smoke on a daily basis (National Health Surv. System Survey 2001). None of our patients were noted to be current smokers and only 3 were noted to have ever smoked. Could our low incidence of vulvar cancer be due to an effective anti-smoking campaign?

Chinese are over-represented in the racial distribution. Could the darker races (Malays and Indians) be protected due to pigmentation? Vulvar cancer is also more common in Western countries where fair skin is prevalent.

Lichen sclerosus is also thought to be a premalignant lesion. Only 16% of our vulvar cancers were associated with lichen sclerosus (8% were also associated with VIN3). Between July 2001 and March 2005, our vulva clinic saw only 35 cases of Lichen sclerosus (10% of all new cases). Could the low incidence of LS locally also explain the low incidence of vulvar cancer?

There is probably an interplay of HPV, genetics and other local factors. What are the other genetic or molecular differences in our population preventing vulvar cancer? Is LS really rare or are the women not coming forward? Perhaps only more international collaborative studies will be able to answer these questions.

Dr Adelina Wong

Consultant Obstetrician & Gynaecologist

Gynaecological Oncology Unit, KK Women’s and Children’s Hospital