降低胆固醇有助于前列腺癌的治疗

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Knocking down cholesterol helps prostate cancer treatment

Weakening cells' membranes may boost radiotherapy efficiency.

Matt Kaplan

Radiation therapy can be made more effective.PunchstockCholesterol-reducing medication might make radiotherapy more effective at treating prostate cancer, according to a preliminary look at patient data.

Prostate cancer affects the male reproductive system and is one of the most commonly diagnosed cancers in men. Depending on the aggressiveness of the disease, it can be ‘cured’ through surgery, in which the tumours are literally cut out, or with radiotherapy. Radiotherapy creates free radicals that damage DNA and stop tumorous cells from growing. But sometimes the cancers spread to other parts of the body or partially resist radiation and grow back later. So researchers are keen to tackle the cancer in as many ways as possible.

Research in animals has hinted that cholesterol-reducing medication may help to slow cancer growth. And in 2006, Cancer Research UK called for more research into the effect, after a study showed a link between high cholesterol and risk of prostate cancer risk.

To investigate, Michael Zelefsky from the Memorial Sloan-Kettering Cancer Center in New York retrospectively studied men who had been treated with radiotherapy for prostate cancer and monitored for an average of 85 months afterwards. Of the 871 men in the study, 168 happened to also be on drugs called statins, which are used to lower cholesterol, while undergoing treatment.

Zelefsky reports today at the American Society for Therapeutic Radiation Oncology meeting in Los Angeles, California, that taking these drugs while receiving high-dose radiotherapy resulted, on average, in a 10% improvement in the long-term cure rates. He adds that the greatest benefits were in patients with the most aggressive cancers.

“This is encouraging, but randomized trials need to be done to be sure there really is something to this,” says Zelefsky.

“If a repeat study confirms that statins, which are effectively non-toxic, can really be used to improve curing methods by 10% then this would be practice changing. I would want to see all of my patients on this,” says Christopher Rose of Valley Radiotherapy Associates in Burbank, California.

Kink in the shield
What the statins are actually doing to damage cancer cells, or whether they might help with other cancers, remains unclear.

Zelefsky suspects that the medication is somehow making the malignant cells more vulnerable to the radiation, effectively functioning as a radio-sensitizer. Reducing levels of cholesterol in the body might weaken the membrane ‘shield’ that surrounds and protects all cells, he says. These shields are in themselves partly made of cholestorol. Weakening this could help the free radicals produced by radiation to damage the target cancer cells more effectively, Zelefsky suggests.

Zelefsky explains that statins are also thought to have cancer-preventative effects: they seem to protect against colorectal and prostate cancer. This, when combined with the the radio-sensitization, could have multiple anti-cancer effects.

It wouldn’t be the first time that two treatments have been seen to work best in conjunction. Hormone therapy to reduce testosterone levels also works extremely well with radiation. “We may see statin medication synergise with radiation just as effectively as hormones did,” says Zelefsky.