Study shows THC increases risk of KS, but other scientists question results

Posted on 08 Aug 2007 at 5:52pm
By Bob Roehr Contributing Writer

Other study shows possibility of sexual transmission of Hepatitis C

A new study by researchers at Harvard Medical School suggests that THC, the major active ingredient in marijuana, makes cells more vulnerable to infection with the Kaposi’s sarcoma herpes virus.

The study was published in the Aug. 1 issue of Cancer Research.

The Harvard researchers’ work was conducted in cell cultures and not in patients, and other scientists have questioned whether those findings would play out in patients.

The purple, blotchy skin lesions of Kaposi’s sarcoma (KS) were a common sight in people with advanced HIV disease prior to the introduction of protease inhibitors, but a reasonably competent immune system seems capable of holding the disease in check.

The study’s lead author, Jerome E. Groopman, said, “These findings raise some serious questions about using marijuana in any form if you have a weakened immune system.”

He said it appears that the THC plays a role in activating the cannabinoid receptors on cell surfaces.

But University of California San Francisco researcher Donald Abrams is skeptical about whether those findings in a test tube transfer to humans with a working immune system.

The oncologist has worked extensively with marijuana and with persons with HIV infection. He points out that marijuana use is widespread in the Bay Area, for both medical and recreational purposes.

But the incidence of Kaposi’s sarcoma has declined dramatically since the introduction of highly active antiretroviral therapy (HAART).

That would not have been the case if Groopman’s findings carried over from the test tube to humans.

Detailed genetic analysis of KS lesions has confirmed the long-held theory that the disease does not behave like other cancers.

A traditional cancer tumor arises from a single cell that begins to divide and replicate wildly. All of the resulting tumor cells are clones of the original one and carry the exact same genetic sequences.

Renan Duprez, working at the Institut Pateur in Paris, biopsied 139 KS lesions from 98 patients. He found that nearly 80 percent of the tumors arose independently from multiple cells, not from a single cell.

This may help to explain why a reasonably competent immune system can hold the infection in check.

The study was published in the July 10 issue of the Journal of the National Cancer Institute.

Hepatitis C

Hepatitis C (HCV) is a common co-infection with HIV among injection drug users, but historically it has not appeared to be readily transmitted sexually, and so is relatively rare among gay men.

But an increase in HCV infection among HIV-positive gay men in Europe is calling that into question.

A presentation at the International AIDS Conference in Sydney looked in detail at the genetic sequences of the HCV infections of 188 HIV-positive gay men in England, Holland, Germany and France. It found 10 distinct HCV clusters of infection, ranging in size from three to 36 individuals.

The authors concluded that the HCV transmissions were the result of increased travel associated with high-risk behaviors of the men.

Previous studies have noted the association between transmission of HCV and a high number of sexual partners, increased incidence of other sexually transmitted diseases, the use of party drugs such as cocaine and crystal meth and engaging in S/M-associated sexual practices.

Those same sexual practices and patterns exist in the U.S. However, there does not appear to be a similar outcome of the sexual transmission of HCV among HIV-positive gay men.

That may be because the incidence of HCV is sufficiently low to not sustain such a pattern of infection.

Or it may be that nobody is looking to see if the pattern is there.

What is gripping New York City is an apparent pattern of HCV transmission from an anesthesiologists to at least three patients through improper infection control techniques.

This article appeared in the Dallas Voice print edition August 10, 2007

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