Early breast cancer: the prognosis at 5 years has improved considerably

Breast cancer is the first female cancer in France as elsewhere (more than 58,000 new cases are discovered there each year). His prognosis has greatly improved, no doubt due to the early management of the disease. In any case, this is the hypothesis adopted by a new study published in the British Medical JournaI.

A much happier prognosis today at 5 years old

UK researchers have analyzed large national data, covering more than 512,000 women with early breast cancer diagnosed between 1993 and 2020. Early is defined as a tumor diagnosed before it is no larger than 5 cm and has spread to more than three lymph nodes. The researchers thus compared the date of diagnosis and the mortality of the patients 5 years later, from January 1993 to December 2015, with a follow-up until December 2020. For each period (1993-99, 2000-04, 2005-09 and 2010-15), the crude annual breast cancer death rate was highest in the five years after diagnosis and then declined.

The data show a significant improvement in prognosis over the years. So :

• The risk of death from breast cancer in the 5 years following prognosis was 14.4% between 1993 and 1999;
• However, it was only 4.9% for women diagnosed between 2000 and 2015.

The study also indicates that when looking only at women diagnosed between 2010 and 2015, the five-year cumulative risk of breast cancer mortality varied significantly between women with different characteristics: it was lower 3% for 62.8% of women but remained above 20% for 4.6% of women.

Therapeutic and diagnostic advances

How can such an improved prognosis be explained? The authors first recall that their observational study does not make it possible to determine the cause(s) of this progress. nevertheless, they put forward several hypotheses:

• The biology of the disease may have changed due to hormonal changes resulting from obesity, use of hormone replacement therapy, and reproductive factors.
• New systemic therapies, including aromatase inhibitors and taxanes, have established themselves in the clinic, and surgery and radiation therapy have become more targeted.
• The use of trastuzumab (Herceptin) in HER2-positive disease has also increased since the mid-2000s, and our results indicate that women with HER2-positive disease had lower breast cancer mortality than those with HER2-positive disease. HER2-negative disease after adjusting for other factors, likely due to trastuzumab use.
• Other factors, such as increased breast cancer awareness, screening, and more sensitive breast imaging techniques, are also likely to have contributed to lower breast cancer mortality.

As we can see, screening is not the only hypothesis put forward by the authors who even state that “improvements in breast cancer mortality observed in women with cancers detected by screening paralleled improvements in those whose cancers were not detected by screening. Therefore, increased screening alone cannot explain the decreases in breast cancer mortality we observed.“.

Today, artificial intelligence could participate in even earlier detection. It is still necessary that the women concerned by the mass screening participate in it. A study revealed last week that one in two women in France do not carry out their organized screening for breast cancer…