We’ve all found ourselves in the middle of conflicting opinions about the advisability of a certain health procedure. A TV news report, a newspaper analysis and a disease website advisory all might offer different takes on the same situation.
Often in those circumstances, the U.S. Preventive Services Task Force (USPSTF), an independent medical expert advisory panel that uses objective science to formulate “best practice” recommendations, helps to sort the wheat from the chaff. As we’ve written, to reduce overdiagnosis and its consequent risks, the task force promotes caution, not indiscriminate testing, in prostate testing and mammography. So its decision last week about CT scans for some smokers and ex-smokers can seem confusing.
As recently as a few months ago, we discussed people who have lung cancer surgery when they don’t have lung cancer, and how widespread screening for lung cancer with CT technology is misguided. So what’s the deal?
“Until recently,” explained the New York Times, “the medical consensus has been that there is too little evidence to justify lung cancer screening, largely because a chest X-ray – the usual screening technique – seldom catches the cancer early enough for lifesaving surgery.
“But that changed in 2010, when a large-scale clinical trial involving 53,000 patients that was conducted by the National Cancer Institute found that a CT scan, which detects much smaller tumors, could reduce mortality by 16 percent among patients at the highest risk of lung cancer. The findings provide the principal basis for the federal panel’s recommendation…”
Here’s the rationale for the USPSTF recommendation:
- Lung cancer is the third most common cancer and the leading cause of cancer death in the U.S.
- The most important risk factor for lung cancer is smoking, which results in more than 8 in 10 of all lung cancer cases in the U.S.
- Although the prevalence of smoking has declined, nearly 4 in 10 U.S. adults are current or former smokers.
- The incidence of lung cancer increases with age, occurring most commonly in people 55 and older.
- Increasing age and cumulative exposure to tobacco smoke are the two factors most strongly associated with the occurrence of lung cancer.
- Lung cancer has a poor prognosis; 9 in 10 people with lung cancer die of the disease.
- Early-stage nonsmall cell lung cancer (NSCLC) has a better prognosis and can be treated with surgery.
So the panel believes that for the highest-risk people-people between 55 and 80 who have smoked at least the equivalent of a pack a day for 30 years, even if they had quit within the last 15 years-the benefit of CT scans outweighs the risk. The recommendation does not apply to people unable to tolerate treatment, such as surgery, if a scan indicates it.
Lung cancer kills about 160,000 people in the U.S. every year. That’s a bigger toll than cancers of the colon, breast, pancreas and prostate combined. For people at highest risk, an annual CT scan could save 20,000 lives-nearly 13 in 100-a year, the panel estimates.
The idea behind the low-dose CT scan is to detect cancer early enough for treatment to be effective. CT scans can detect much smaller tumors than chest X-rays.
For many people, the harm of screening is finding an abnormality that looks like cancer but will never develop into anything threatening yet could prompt unnecessary surgery and invasive tests like biopsies. Those procedures have their own risks, including unnecessary stress and infection.
One source for The Times story said that little was known about the cumulative radiation risks of years of CT scans. The task force recognized those risks, but said the number of lives saved by the screening significantly would outnumber the lives lost from cancers from radiation exposure.
Dr. Peter B. Bach, a pulmonologist at Memorial Sloan-Kettering Cancer Center in New York, told the Times that the National Cancer Institute’s trial was conducted at top clinical research centers, and that broader use of the technology where the quality of medical care is lower could lead to many more medical procedures that were not needed in the first place.
“This is going to be very hard to replicate in real life,” Bach said about the trial results.
He has created an online lung cancer screening decision tool to help people assess their personal variables and whether CT screening makes sense for them; link to it here.
The USPSTF recommendation is in draft form. The panel will issue its final recommendation three to six months after the public comment period, which ends Aug. 26. Read it and weigh in with your opinion here.