The threat of cancer is daunting for many and health care providers as well as the general public have long held beliefs that screening for the presence of cancer will aid in early detection as well as reduce mortality due to cancer. A startling new study by Dr Vinay Prasad and colleagues has found that screening for cancers may not be all that good.
Cancer screening involves checking for cancers when the patient shows no symptoms of the disease. This, doctors believe will -
- Aid in detecting cancers at an early stage.
- Be effective in treatment procedures.
- Reduce cancer mortality rates.
‘Cancer screening procedures should be restricted to high-risk groups, considering the harm associated with them.’
AdvertisementConcerns Raised by the Study:
- Cancer screening may decrease mortality that is disease specific but does not affect overall mortality rates
- Deaths are associated with the negative impact of cancer screening procedures
- False positive tests
- Increased attention, diagnosis and cancer treatment afforded to tumors that are harmless
Colon Cancer Screening Study at MinnesotaColorectal cancer i.e the cancer affecting the lower digestive system comprising of colon and rectum is the most common cancers affecting both men and women, Stool tests and endoscopic tests are used in the screening of colorectal cancer.
The study by Moayyedi and Achkar showed that -
- 128 deaths due to colon cancer per 10,000 in the screened group
- 192 deaths due to colon cancer in the control (non-screened) group
- Overall mortality - 7111 deaths per 10,000 in the screened group and 7109 deaths per 10,000 in the control group
Prostate Cancer ScreeningProstate cancer is one of the most common forms of cancer among males. The limiting factors raised by Dr Prasad and colleagues concerning prostate cancer include -
- Prostate cancer screening is based on detecting prostate specific antigen (PSA) in the blood stream. The detection of this antigen can lead to false positive results. This leads to one million prostate biopsies every year.
- The surgery for acquiring prostate biopsies requires hospitalization with the risk of death.
- Men who have been diagnosed with prostate cancer after cancer screening methods are more likely to -
- Have a heart attack within one year of diagnosis
- Commit suicide due to the diagnosis
- Die of treatment associated mortalities even before symptoms set in
The study also showed the skewed impressions about cancer screening among women who underwent mammography, PSA screening or even cervical smear test.
- 68% of women believed that mammography would decrease their risk of developing breast cancer
- 62% thought that the risk of breast cancer was reduced by half
The limitations associated with screening procedures should dissuade people from taking up screening unless they are in the high-risk group. For example, heavy smokers should be screened for lung cancer while it may make little sense to carry out lung screening procedures for people who have never smoked or associated with low air pollution levels.
In the future, better screening procedures that reduce the risks associated with screening and more intensive studies that focused more on non-cancer mortalities between the screened and the non-screened groups would benefit the cause of cancer care and treatment.