April 10 (UPI) -- A new study sheds light into why the prevalence of cervical cancer and HPV infection rates are drastically lower in certain regions of the world.
Many cervical cancer deaths worldwide occur in low- and middle-income countries, however, areas of Western Asia, including Saudi Arabia, have low rates of cervical cancer even though there is a lack of screening or vaccination programs against the human papillomavirus, or HPV, a sexually-transmitted disease that is the main cause of cervical cancer.
To better understand the cause behind this, Dr. Ghazi Alsbeih of the King Faisal Specialist Hospital & Research Center in Saudi Arabia and his team collected tumor samples and demographic data from 232 patients with cervical cancer.
Those samples were compared to 313 matched controls of patients without cancer.
Researchers found that cervical cancer in this group had two peaks of increased incidence at age 43 and 61. Globally, 85 to 99 percent of patients with cervical cancer are HPV-positive, however, only 77 percent of the patients in the Saudi national cohort were HPV-positive.
"As cancer development takes years to decades, the first peak could be a consequence of early sexual encounters, which often occurs at the end of the teenage period to the early thirties, while the second rebound could correspond to new encounters later in life," Alsbeih said in a press release. "The latter is generally occasioned by separation, failure of a first marriage, or simply second marriages in polygamous societies, which brings in an added risk of HPV infections as the number of lifetime sexual partners increases."
Researchers found that HPV-negative patients were more likely to have a particular variant in the gene that encodes the p53 tumor suppressor protein, a cytosine, or C, rather than a guanine, or G, in the DNA code that leads to the production of a proline rather than an arginine amino acid in the translated protein.
This C variant may be associated with a reduced chance of HPV infection, the reduction of which is also associated with a lower risk of cervical cancer.
Researchers acknowledge that different cultural norms may also contribute to the lower rates of cervical cancer in Saudi Arabia.
The study was published in Cancer.