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TreatmentUpdate 173Volume 21 Issue 4 2009 May/June II CANCER: A. Concern about cancer risk with raltegravirHIV infection can weaken the immune system, increasing the risk for life-threatening infections and certain cancers. In the early stages of clinical trials with raltegravir there were reports of an apparent increase in cancers seen in some raltegravir users. Concerned about this finding, researchers compared cancer cases seen in several raltegravir trials over time. Their findings suggest that there is no significantly increased risk of cancer due to raltegravir exposure. Possible reasons for the apparent increase in cancer cases are discussed later in this report. Study detailsResearchers analysed data from five clinical trials that had these identifying names:
The first three trials enrolled treatment-experienced people and the last two trials enrolled people who had never previously received anti-HIV therapy. The average profile of treatment-experienced participants at the time they entered the study was as follows:
The average profile of the people who were new to anti-HIV therapy was as follows:
A note on clinical trialsBefore reading the results of the cancer analysis it is important to bear this note in mind: Large clinical trials do not recruit all of their participants all at once. Rather, recruitment can take weeks or even months as people gradually join the trial. Results—cancer in raltegravir usersIn total, researchers examined health information from 1,039 people exposed to raltegravir and 605 who received placebo. Using a strict definition of cancer, here is what happened: Until the second month of the trials, cancer rates were similar in people who received raltegravir and those who received placebo or another agent. But after the second month of the study, cancers became more common in raltegravir users and the number of new cancers stabilized shortly after that time. After about the third month of the study, cancer rates became essentially stable in raltegravir users, affecting about 1% of them over the next 20 months—the extent for which data was made available for this analysis. Results—cancer in people who received placeboUntil the second month of the trials, cancer rates were similar in people who received raltegravir and those who received placebo or another agent. After the third month of the study, cancer rates in people receiving placebo or another agent also rose such that by the fourth month of the study cancer rates were the same in both study groups. After the sixth month of the study, cancer rates continued to climb in people receiving placebo or another drug and then stabilized around the 12th month. Overall, slightly more than 2% of people in this group developed cancer over the course of about 20 months. These differences in rates of cancer between people receiving raltegravir and those who received placebo were not statistically significant. Focus on cancersIn total, 46 participants developed 53 cases of cancer during the double-blind phase of the study. Commonly detected cancers included the following:
It is noteworthy that cancers were more common among treatment-experienced people. This is probably due to their weaker immunity as suggested by their generally lower CD4+ counts upon entering the study. Tumours tend to take years to develop and it is possible that because treatment-experienced patients were sicker, their tumours were more advanced and could grow faster. Even though highly active antiretroviral therapy (HAART) can quickly raise CD4+ cell counts in the blood—within days of initiating therapy—this increase in the first few weeks after starting HAART is merely a feature of redistribution as T-cells move from the lymph nodes to the blood. It takes several months before new and more functional T-cells and other parts of the immune system can regenerate and begin to help heal the damage wrought by HIV. Until the immune system gets repaired, there is still a risk for life-threatening infections and cancers during the first two to three months of anti-HIV therapy, particularly in people who initiate therapy at low CD4+ cell counts. People taking raltegravir will continue to be monitored for the development of cancer. However, so far the data show that there is no increased risk of cancer in people due to exposure to raltegravir. REFERENCES:
Created on: 2009 June 9 Author: Hosein SR |
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Decisions about particular medical treatments should always be made in consultation with a qualified medical practitioner who is knowledgeable about HIV-related illness and the treatments in question. MORE | |