HPV is associated with the development and progression of several types of cancer

Every year, 700,000 new cases of Human Papillomavirus (HPV) infection emerge in Brazil, according to estimates from the Ministry of Health. The virus has more than 100 subtypes, those considered oncogenic have a greater risk of causing persistent infections and developing lesions that, if If left untreated, they can cause cancer of the cervix, anus, vulva, vagina, penis and oropharynx, warn researchers from Hospital Ophir Loyola (HOL), in Belém, a reference in Oncology in the North region.

Associated with more than 90% of cases of genital warts, cervical and anus cancer, HPV infection is transmitted sexually, when there are no protective measures. Despite the guidelines on the use of condoms in all sexual relations and the offer of the vaccine in the Unified Health System (SUS) for children and adolescents aged 9 to 14, and also for people with low immunity, the infection affects many people.

According to experts, low adherence to vaccination campaigns in Brazil is linked to misinformation generated by anti-vaccine groups and the myth that immunization encourages the early start of sexual life.

Member of the HOL Clinical Research Laboratory, professor Diego Alcântara clarifies that the virus infects anyone, whether through oral-genital, genital-genital or even manual-genital contact, and can occur even in the absence of vaginal or anal penetration.

Contagion – According to the expert, an infected but asymptomatic man often has sexual intercourse with a woman without using a condom and ends up transmitting the virus. “It is within the female anatomy that the Papillomavirus has a greater capacity to proliferate and cause the characteristic lesions of the infection. Vaccination not only prevents, but also reduces recurrence, especially of cervical cancer in women, penile cancer in men and anal canal cancer, where the virus has been shown to proliferate more”, highlights Diego Alcântara.

Campaigns and other screening strategies help to detect lesions with a high cancer risk, enabling treatment. Early diagnosis reduces mortality rates and considerably increases the survival rate. In women, precursor lesions are detected through a cytological examination, known as a Pap smear.

Transmission of the virus occurs through direct contact with infected skin or mucosa. “HPV infects the mucosa and secretes proteins that pass through the cell’s DNA and activate a protein called ‘P16’. This protein initiates a series of changes that facilitate infection of the host, but it is persistent inflammation that promotes or increases the chances of cancer arising”, says Rommel Burbano, coordinator of HOL’s Molecular Biology Laboratory.

The subtypes are classified based on the potential risk for the development of malignant neoplasia, and are divided into low-risk HPV and high-risk HPV. The first group includes HPV6 and HPV11, which are generally not associated with the etiology of cancer, but are present in benign skin or mucous membrane lesions, such as warts. In women, these lesions are commonly present on the vulva, vagina, cervix and anal canal. Among men, they are seen in the penis, scrotum and anus.

The second group is made up of HPV16 and HPV18, responsible for most cases of HPV cancer. They cause precancerous lesions that evolve into malignant tumors. These are subtypes highly associated with carcinogenesis.

Above average prevalence – Ophir Loyola Hospital works in teaching and researching cases treated at the institution. Over the years, researchers have concluded that the prevalence of HPV in the types of cancer most commonly associated with the virus in Pará is above the average for the world population, and even above the Brazilian average.

“Cervical cancer, for example, has an average prevalence of 13.4% in the State, 6% in the country and 3.1% in the world. For malignant neoplasia of the penis, the average is 1.1% in the State, 0.2% in the country and 0.2% in the world. And regarding the average number of anal cancer caused by the virus, it is 1.2% in the State, 0.3% in the Country and 0.3% in the world”, informs Diego Alcântara.

Vaccine potential – In 2017, an investigation carried out with cervical cancer patients treated at HOL, and at another institution in Rio de Janeiro (RJ), confirmed that the HPV4 vaccine, adopted since 2014 by the Health System, can potentially reduce approximately 70% of the incidence of cervical cancer. The implementation of the new HPV9 vaccine has the potential to increase the impact of immunization by 85%, helping to reduce the incidence of cervical cancer.

A 2018 study on anal carcinoma demonstrated that individuals with HPV infection had no residual tumors after chemoradiotherapy. “This correlation is valuable and can direct future therapeutic approaches in the anal canal. Another analysis, published in an international oncology research journal in 2020, demonstrated that the presence of HPV in patients with oral carcinoma is a factor that reduces the aggressiveness of the tumor”, highlights Professor Diego Alcântara.

Regarding penile cancer in the region, HPV infection is found in 60% of cases. However, this rate did not demonstrate an association with a worse prognosis.

Serology – In view of all the relevant results in the population of Pará, HOL will start offering the HPV serology test later this year. “The aim is to identify individuals at high oncogenic risk early, avoiding the appearance of pre-malignant lesions and, therefore, contributing to the reduction of cancer cases etiologically linked to this infection”, says Rommel Burbano.

If cancer caused by the virus is detected in the patient, it is possible to define the most appropriate treatment. This is because the virus is sensitive to chemotherapy and radiotherapy. “In this case, patients do not need to undergo invasive surgical treatment. The chances of cases of tumors of the penis, head and neck and anal canal being associated with HPV are above 70%. This is information that can change treatment and generate savings for public health”, concludes coordinator Rommel Burbano.