How Did CNBSS Influence Guidelines for So Long and What Can That Teach Us?

Round 1

Reviewer 1 Report

I reviewed the manuscript “How did CNBSS influence guidelines for so long and what can that teach us”? by Dr. Shushiela Appavoo.

I wish to congratulate the author for such an excellent analysis of a long-lasting and very serious problem affecting medical practice. The message is clear, the analysis is impeccable and the conclusions are well substantiated.

There is one serious defect in the CNBSS which has not been given adequate consideration during the past four decades when so-called expert groups have evaluated the population-based randomized controlled trials. The CNBSS is not a population-based trial, instead, it is a recruitment trial based on a mixture of motivated volunteers augmented by women referred by their physicians. This crucial factor is not mentioned in Dr. Appavoo’s manuscript. Only 26-27% of the target population were enrolled in the trial, adding an additional serious bias to any result or conclusions. It would be extremely important that this defect is also mentioned in the manuscript in addition to the other, well described flaws in the CNBSS.

The reference list is well balanced, but this reviewer would suggest adding the following reference citation which clearly documents the outlier status of the CNBSS: https://pubmed.ncbi.nlm.nih.gov/25413699/

The English language is superb and needs no corrections (however the Publons manuscript review form does not offer this choice!).

Author Response

Thank you for your kind words. I have incorporated some edits to reflect the important problem with volunteer recruitment in the CNBSS and included your suggested reference as well as a reference from Dr Baines which discussed their admitted difficulties in finding volunteers, which lends plausibility to the eyewitness accounts that they accepted patients who were "volunteered" by surgeons.

Reviewer 2 Report

Summary:  

This commentary addresses the flaws in the two Canadian National Breast Screening Studies (CNBSS) and why these studies continue to inappropriately influence breast cancer screening guidelines, even in the face of these flaws. It further suggests reforms in the bodies that produce the guidelines to assure that flawed studies such as the CNBSS be eliminated from consideration in the future.

Review:

The commentary is quite complete, with documentation of the flaws in the CNBSS carefully explored and documented.  Given the gravity of the flaws and their apparent consequences in endangering women’s lives, the commentary seems very relevant to the efforts of the medical community to further improve health care. There do not appear to be any serious gaps in knowledge, and the extensive references cited all seem appropriate.

Specific comments:

You make a strong case for reform of the bodies currently promulgating medical guidelines, with a well-constructed collection of cogent arguments to support your case.  I offer a few specific suggestions:

Lines 170-171:  The sentence beginning “Specialist bias…” is unclear to me as to what is intended here.  Please clarify or rephrase.

Lines 200-201:  The sentence beginning “Quality reviews…” is difficult to follow and awkward, with what seem to be double negatives.  Please rephrase.

Line 221:  The term “Mammo Wars” may be a bit inflammatory.  Would suggest toning this phrase down a notch.  The phrase “Screening controversy” might be more appropriate.

Line 289:  I would suggest adding the word “other” before “major extant CTFPHC guidelines”, for clarify. 

Line 322:  The phrase “Roughly contemporaneously” seems awkward.  Perhaps “At approximately the same time” might work better.

Lines 324-325:  This sentence, although perhaps true here, might be a bit over the top.  I would consider eliminating it.

Author Response

Thank you for your excellent constructive comments. I have made the recommended adjustments and I hope these have provided adequate clarification. 

Shiela