Tuesday, July 19, 2016
Preventing Cervical Cancer in Tanzania
I visited Tanzania again this summer, once again helping a group of amazing University of California, Irvine medical students with their summer not-a-vacation trip to teach bedside ultrasound and do other research projects.
One of the projects this year sprung out of a request by a doctor we have worked with on Ukerewe Island. The island he serves is rural, primarily supported by fishing, and has a high rate of sexually transmitted diseases due to fishermen visiting prostitutes on the mainland and bringing home infections to their wives and girlfriends. This translates to high rates of HIV infection, pelvic inflammatory disease and the spectrum of disease caused by human papillomavirus (HPV). HPV can cause genital warts, which are only mildly distressing, but it can also set in motion cellular changes of the cervix that can lead to cervical cancer. Tanzania has a distressingly high incidence and death rate from cervical cancer and this Tanzanian physician asked one of the students if we could do a project that would help reduce cervical cancer.
The high mortality and incidence of cervical cancer in sub-Saharan Africa can be (and has been) addressed in many ways. Primary prevention would involve using condoms or maintaining celibacy or reliable monogamy. We have a vaccine now that can prevent persistent infection, but it is still very expensive and not used much in resource poor countries like Tanzania. Pap testing is the method we use in the US to prevent cervical cancer, and its use is widespread and effective here. It involves taking a sample of the cells of the cervix during a speculum exam, sending this to a pathologist for evaluation, and repeating that test at regular intervals. Abnormal pap tests are reported to the patient who is notified to return for further testing and eventually removal of the infected tissue if it persists. The abnormal tissue is visualized by applying acetic acid to the skin of the cervix, then using a cervical microscope or colposcope to either biopsy, cut or freeze away abnormal tissue. In most of Africa this is not even vaguely practical since women go to the doctor infrequently and speculum exams are not often performed. It is not always practical to contact people by phone, and they often come from far enough away that returning for multiple visits to deal with an abnormal pap is not likely to happen. In addition, were physicians to start performing regular pap testing, there are not enough pathologists to process the specimens.
About 10 years ago I read an article in one of the large medical journals which described an abbreviated screening test for HPV infection in which vinegar (acetic acid) was applied to the cervix, abnormal areas that looked HPV infected were identified with the naked eye and those areas were simply frozen, destroying the infected and precancerous tissue. This sounded amazing. Since then this procedure has become well accepted, though certainly not universally available, to people living in many African countries. The World Health Organization has studied it and pronounced it to be practical and recommends it for resource poor settings.
The students heard about an organization, CureCervicalCancer, which teaches healthcare workers visual inspection with acetic acid (VIA) and supplies a gun which can deliver compressed carbon dioxide (available in poor countries because it is used to make soda pop) to the infected tissue of the cervix, to freeze it off.
This year several people affiliated with Cure Cervical Cancer came to Tanzania with us, trained Tanzanian MD and non-MD healthcare workers to perform visual inspection and cryotherapy and gave them supplies they would need to make the service ongoing.
The idea of being able to provide that kind of immediate and practical service was very exciting. I just thought it wouldn't work. Doctors and nurses in Tanzania are so overworked that I doubted they would come for a few days to learn a new technique. I also thought that a pelvic exam using a speculum would be a VERY hard sell for women who have never had a pelvic exam, especially since they would be feeling fine. I thought that the doctors wouldn't have time to continue to do these exams after we left. It turns out I was wrong: health care workers were enthusiastic and attended the trainings and women lined up for testing.
The first day we had fewer patients than the leaders felt was acceptable, about 60 patients total I think. So the students who knew Tanzania from previous trips made flyers which they handed out, used their large word of mouth network and finally hired guy in a truck with a loud speaker to drive around the streets advertising the free clinic. The next two days doubled or even tripled the number of patients screened! Several cases of HPV infection were seen and treated and a few early cervical cancers were identified and referred for likely surgery.
This project may persist. They were able to train people from the city of Mwanza as well as Ukerewe Island and they promise to continue to do screening after we leave, free of charge. We shall see. There is some kind of audit planned for 6 months out. Clearly more nurses and doctors need to be trained to do this. This is clearly the right kind of screening to do in this setting and may reduce the burden of cervical cancer. In our screening clinic the host hospital also offered free HIV screening which was fantastic since treatment of HIV in Tanzania is free. Cervical cancer is more common and more aggressive in HIV infected women, so combining the screenings is really powerful.
I think this will help. I do have some reservations, though. In the US, 80% of people will be infected with HPV during their lifetimes, and the vast majority will kick it and have no ill effect. At any one time, I've read, 10% of women will have HPV infections. Only a fraction of the types of HPV that are out there are able to cause cervical cancer. The point here is that all HPV infection does not necessarily need treatment. We don't have evidence yet that VIA with cryotherapy saves lives, though it seems likely that it will and there have been mathematical models that evaluate this. VIA is, though, a sustainable method to treat HPV infection early and thus to prevent late sequelae including cancer Clearly real prevention of infection would be the most valuable intervention in prevention of cervical cancer. This could be by vaccination, if the vaccine were affordable, or use of condoms to prevent transmission of infection. More important even than that would be changes that allow women to have more control of what happens to them sexually. This will require improved education and economic opportunities so that women have value in the society outside of their roles as mates and mothers.