Individual point of view

The key fact for a woman considering whether or not to participate in screening is that screening is a lottery.

Some women will win, by curing a cancer that would have been fatal without screening.
The probability of winning is unknown, but it is likely to be between 2 and 5 chances in 1,000 for a woman who strictly adheres to the screening program (a mammogram every 2 years from age 50 to 74).

Some women will lose out, experiencing the psychological, physical and social consequences of overdiagnosis and overtreatment.
The probability of losing is also unknown, but it is likely to be between 9 per 1,000 (slightly less than 1 chance in 100) and 40 per 1,000 (4 chances in 100) for a woman who strictly adheres to the screening program (one mammogram every 2 years from age 50 to 74).

And no one can predict who will win and who will lose.
However, it is important to play down the stakes a little by reminding ourselves that the vast majority of participants will neither win nor lose.

Collective point of view

A well-founded decision is impossible from the standpoint of the decision-maker considering whether or not to continue screening by invitation as long as the estimation of the benefits and risks is uncertain.
The benefit/risk balance ranges from 1 to 2 overdiagnoses for 1 breast cancer death prevented to more than 20 overdiagnoses for 1 breast cancer death prevented. With such a broad range, how can a decision be made ?

In the face of so many uncertainties, continuing screening by invitation may be justified, but only under two conditions :
- first, to promote high-quality randomized controlled trials to better understand the benefits and risks of screening. And we can see how MyPeBS is a lost opportunity.
- to ensure that communication about screening is fair and complete :
presenting both the risks and benefits in a balanced manner,
presenting all available data, not just those most favorable to screening.

Beyond statistical uncertainty

The difficulty, from both an individual and a collective standpoint, stems from the fact that we are comparing :
- on the one hand, benefits expressed in years of life gained
- on the other hand, risks represented by years of life wasted by overtreatment.
Some will argue that “you can't make an omelette without breaking a few eggs”, and that overtreatment is an unavoidable cost of saving lives. Others, on the other hand, will believe that overtreatment, with its physical, social, and psychological consequences, is an excessive price to pay for the few lives saved.
There are not just differences in opinion about the effectiveness of screening and the frequency of overdiagnosis behind these disparities in opinion. There are also various "philosophical" viewpoints on the cost of life and the cost of loss of quality of life. And this is a matter of personal conviction rather than scientific evidence.

Conclusion

Despite all of the uncertainties, two things are certain :

• Not participating is just as respectable as participating. As a result, women should not feel guilty if they refuse screening.
• Women have the right to full and fair information, which allows them to make their own decisions without being influenced in any way.