RE: Further comments on the Canadian Task Force's breast screening guideline.
References
Martin J. Yaffe. Revamp governance of Canadian Task Force on Preventive Health Care. CMAJ 2020;192:E145-E145.
2. Klarenback S, Sims-Jones N, Lewin G, et al. for the Canadian Task Force on Preventive Health Care. Recommendations on screening for breast cancer in women aged 40–74 years who are not at increased risk for breast cancer. CMAJ 2018;190:E1441–51.
3. Klarenback SW, Moore AE, Thombs BD. The authors respond to: “Revamp governance of Canadian Task Force on Preventive Health Care”. CMAJ 2020 February 10;192:E146-7.doi: 10.1503/cmaj.74313.
https://clinicaltrials.gov/ct2/show/NCT01081288 (accessed 2020 May 30).
5. https://files.digital.nhs.uk/publicationimport/pub20xxx/pub20018/bres-scre-prog-eng-2014-15-rep.pdf (accessed 2020 May 30).
In his letter (1) Dr. Yaffe clearly describes the problems with the Canadian Task Force’s guideline on screening mammography, especially for women aged 40 to 49 years, arising from its unwillingness to consider any evidence except RCTs . However, the same issues affect their recommendation against breast self-examination which is based on two RCTs of poor quality from countries with completely different cultures and health care systems (2). Their recommendation against clinical breast examination is based on no evidence whatsoever (2). These guidelines of course leave women in the 40 to 49 year age group in the unenviable position of having no means of early detection of breast cancer. Surely the Task Force’s only honest conclusion would have been to state that it could not find any currently relevant evidence which it was willing to use and therefore it could not provide a guideline on screening mammography.
In their response (3) the Task Force refers to an RCT which is currently underway in the United Kingdom. However, this trial (4) began in 2009 and it was not until 2015 that NHS breast screening became “mostly digital” (5) and the trial only recruits women age 47 years and older (4), so it will not provide an answer to the effectiveness of screening in the 40-49 year age group using modern equipment.
The Task Force does recommend that women should discuss the benefits and harms with their physician. Provincial screening programs provide data annually on the likelihood of a screening study being abnormal , the likelihood of the abnormality resulting in a biopsy and the likelihood of the biopsy being positive for some type of carcinoma (6), the three types of information that would most help a woman make her decision. To achieve its goal “to support primary care providers to deliver the best possible preventive health care” the Task Force should have recommended that physicians use this information which reflects current developments in their discussions with their patients rather than the “tools” the Task Force provides.