Wed, Mar 25, 2015 - Page 3 News List

Pap test results prompt doctors to urge DNA method

By Stacy Hsu  /  Staff reporter

Several gynecologists yesterday advised women to have annual human papillomavirus (HPV) DNA tests as well as Pap tests because the latter can sometimes give false negative results that could lead to delays in diagnosis and treatment.

Formosa Cancer Foundation vice president Jacqueline Whang Peng (彭汪嘉康) said the incidence of invasive cervical cancer in Taiwan has dropped significantly — by 63 percent — from 27 per 100,000 in 1992 to 10 per 100,000 in 2011, thanks to the increase in women having regular Pap tests since 1995.

“Despite the noticeable decline, the smear test’s occasional production of false negative results has impeded diagnosis of the second-most common cancer of female reproductive organs,” Whang Peng told a news conference in Taipei.

Several researchers have suggested that Pap testing has a detection rate of about 60 percent and that the chance of a false negative is higher for cervical adenocarcinoma, a type of cervical cancer, since it generally originates higher up the cervical canal, which is harder to reach and sample, she said.

Taiwan Association of Gynecologic Oncologists president Twu Nae-fang (屠乃方) said that virtually all cervical cancers are caused by HPV infections, including 14 high-risk, or cancer-causing, strains and dozens of low-risk, or wart-causing, ones.

“Of the high-risk strains, types 16 and 18 are particularly notorious, because they are responsible for nearly 70 percent of cervical cancer worldwide,” Twu said. “A further breakdown shows these two strains account for 82 percent of cases of cervical adenocarcinoma, compared with just 70 percent of squamous cell carcinoma, the most common subtype of cervical cancer.”

Twu said research showed that women who test positive for infection with HPV types 16 and 18 are 35 times more likely to develop precancerous cervical lesions than their HPV-free counterparts.

Given that an HPV DNA test can tell whether and which types of HPV a woman has, it would allow her to take the necessary precautions before the infection can develop into cancer, such as having a biopsy to test for any abnormal or precancerous conditions in the cervix or having more frequent Pap smears, Twu said.

Dianthus MFM Clinic vice superintendent Chong Kian-mei (張建玫) said her mother was diagnosed with stage II cervical cancer despite a negative Pap test result two years ago.

“As a gynecologist-obstetrician, I have always regretted not arranging an HPV DNA test for my mother sooner,” Chong said. “If I had, her condition might have been detected earlier and she could have been spared the suffering of chemotherapy.”

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