Another Gina Kolata special in today's New York Times, this time asking why Americans ignore proven cancer prevention drugs while gulping unproven supplements. Why should the drug industry bother developing such drugs when people won't take them and they can make so much more money treating the disease, she asks.

Here's some unanswered questions I had while reading the story:

• How many men take finasteride (generic Propecia, $2 a day) or dutasteride (GlaxoSmithKline's Avodart, $3.50 a day) to prevent prostate cancer compared to men who take unproven supplements that falsely claim to prevent prostate cancer?

Answer: It wasn't in the story, even though the story claimed "the drugs that work are largely ignored" while "supplements that have been shown to be not just ineffective but possibly harmful are taken by men hoping to protect themselves from prostate cancer."

• How many men would have to take finasteride or dutasteride to prevent the 50,000 cases of prostate cancer per year the story said could be prevented by taking those drugs?

Answer: It wasn't in the story, even though there is widespread skepticism in the medical literature about the value of finasteride and dutasteride (known as 5-alpha reductase inhibitor or 5-ARI therapy) in reducing prostate cancer risk. Indeed, a clinical practice guideline issued by the American Society of Clinical Oncology and the American Urological Association and authored by NIH cancer prevention specialist Barnett Kramer was summarized this way:

5-ARI therapy during a 7-year period reduces the relative risk of developing prostate cancer by 25%. The absolute risk reduction however was only 1.4% which leads to about 71 persons needed to treat to prevent one cancer. Another way of looking at this result is that if 1000 men were followed over a period of 7 years, 59 would be expected to develop prostate cancer, and if they all took the 5-ARI, 45 would still develop cancer.

Let's take this analysis one step farther. Treating 71 people for seven years at $730 per year (the cheaper $2-a-day drug) would cost over $350,000 to prevent one prostate cancer case, while subjecting all of them to the potential side effects of decreased sex drive and erectile dysfunction. Meanwhile, the one prevented cancer had the probability of being non-fatal (i.e., the person would die of something else before succumbing to cancer, which is why many older men diagnosed with prostate cancer prefer "watchful waiting" to aggressive treatment). Is that a wise expenditure of health care system resources? Alas, the story provides no insight into this question or information on which to make a decision.

• How does the benefit of taking tamoxifen or raloxifene to prevent breast cancer in women at high risk compare to the risk of contracting uterine cancer from taking the drugs?

Answer: I don't know, and can't figure it out from the apples and oranges data in the story. We're told that women over 55 at high risk (previous breast cancer and/or had early menstruation, a late child and a family history of the disease) have a lifetime risk of 20.5 percent, while all women have a lifetime risk of 9.8 percent, and that the drugs cut that risk in half. But we're also told the drugs cause 2 cases of uterine cancer per year for every 100,000 women who take them. Okay, that's one in 50,000. Can you tell me how many women get breast cancer in the above profiles? I can't figure it out. As for cost data, not a word beyond the daily cost of the drugs.

Now let's look at the most effective prevention strategies mentioned in the story. There's just one paragraph about smoking, the single biggest cause of cancer, and it's buried deep within the story.

There's also just one paragraph on the sharp drop in breast cancer rates from the widespread abandonment of hormone replacement therapy after the Women's Health Initiative study came out in 2002 showing that taking estrogen-like compounds sharply increased cancer risk. Think about it. Reducing exposure to a single risk factor -- a drug! -- almost immediately led to a 15 percent reduction in the third most common cancer. You'd think it would have gotten a little more play in a story focused on the role of drugs in preventing cancer.

Meanwhile, there is a long discussion about the failure of dietary and micro-nutrient interventions to prevent cancer, with quotes from the chastened researchers who have pursued this path. But there is not a single paragraph that talked about environmental causes of cancer that could be addressed to rein in the disease. They include curbing diesel smoke and other air pollutants, and limiting known chemical carcinogens that are present in the workplace and spilled into the environment.

The causes of cancer are complex and interactive. A variety of factors come into play, including genetics, environmental irritants, lifestyles choices and bad luck (our cells are constantly reproducing, and the body's safety system for correcting mistaken DNA transcription sometimes fails; a certain amount of cancer is inevitable, especially as people age).

A story on cancer prevention that focuses almost exclusively on the drugs not taken offers an impoverished view of how to prevent "the dread disease."

(An earlier version of this story miscalculated the cost per cancer case avoided with finasteride. It would cost over $350,000, not over $50,000 as previously stated.)