A prophylactic vaccine is effective in preventing the development of breast cancer in mice, according to an American study reported in the journal Nature Medicine.
The authors of the study emphasize that it will be some time before the preparation is available on the market. In the near future, they plan to test it in clinical trials on patients.
While vaccines are the most effective disease prevention tool, especially infectious disease, in the case of cancer, researchers focused mainly on therapeutic vaccines to treat existing tumors. In early May 2010, the world heard about the first of its kind – a therapeutic vaccine for prostate cancer – which was approved for use in the USA.
The main problem with developing prophylactic cancer vaccines is that the antigens (or characteristic compounds) of cancer cells are variants of molecules found in healthy cells in the body. A vaccine directed against them could therefore trigger a strong autoimmune reaction, i.e. aggression of the immune system against its own cells, including healthy ones.
The only exceptions to this are vaccines designed to prevent viral cancers, which include vaccines against the HPV virus, which is responsible for cervical cancer, and the HBV virus, which can lead to liver cancer. But here the matter is much simpler, because the immune system recognizes viruses as something foreign.
In a study on mice, scientists from the Cleveland Clinic (Ohio) selected alpha-lactalbumin as a component of a potential vaccine to prevent breast cancer. It is a protein produced in excess by the cells of most breast cancers, while healthy mammary epithelial cells only produce it during the lactation period, which reduces the risk of the immune system becoming aggressive to healthy tissues.
To see if a vaccine containing alpha-lactalbumin could be an effective protection against breast cancer, scientists tested it in mice genetically predisposed to breast cancer. Half of them, at 8 weeks of age, administered this protein together with the adjuvant, ie a compound that enhances the immune system’s response to vaccination, and half of them administered only the adjuvant.
They found that at 10 months of age all unvaccinated females had breast cancer, while none of the vaccinated group.
In further tests, the researchers also showed that the vaccine can inhibit the growth of breast tumors that were implanted in mice with a defect in the immune system. It was only effective when it was given on days 5 or 13 after the cancer cell transplant, but not later.
We hope that one day this vaccine will be used in the prevention of breast cancer in adult women, in the same way as other vaccinations have been used in the prevention of many childhood diseases – comments Vincent Tuohy, who leads the study. In his opinion, if the vaccine was as effective in humans as it was in mice, the chances of eliminating breast cancer would increase significantly.
Before this happens, however, scientists must check the safety and effectiveness of the preparation in clinical trials on patients.
The researchers reminded that nowadays women can lower the risk of breast cancer by reducing alcohol consumption and taking care of a slim figure by following a less caloric diet and regular exercise (PAP).