Monday, 8 May 2017

What if I decide to do nothing?

TIME magazine has surprised us with a question on its front page: "What would happen if I decided to do nothing?" Desiree Basila, a 60-year-old teacher, had just been diagnosed with ductal carcinoma in situ (DCIS) and, overwhelmed by the aggressiveness of the treatment proposals offered to her, began to investigate on her own and realized that there were many unknown elements about the progression of this type of injury and also saw that there was no agreement in the scientific community on what should be the most appropriate therapy for her case. For this reason she made a bold decision and asked her oncologist to do nothing, which resulted in two checks a year and a treatment with Tamoxifen, a drug that blocks estrogens that could cause the tumour to grow.

The case of Desiree Basila is quite valuable because when she made this decision, 8 years ago, it was not yet known that the mortality of women with DCIS, regardless of the type of treatment they adopt, is 3.3%, a figure comparable to that of the general population, and it was also not known that chemotherapy has no effect on tumours in initial staging. But to better understand the pressure that Desiree had to endure, it should be added that the attitude of most oncologists, even in the case of DCIS, was, and remains, "the sooner the better and the more the better."

On the other hand, JAMA Internal Medicine, in the section "Less is more", has just published "Breast cancer screening, incidence, and mortality across US counties", a study of 16 million women from 547 US counties , of whom they chose 53,207 who had been diagnosed with breast cancer in the year 2000, and observed what had happened 15 years later. The scientific work takes advantage of the fact that, in the US, the implantation of breast cancer screening programs is very variable, and because of this, it has been possible to relate the level of implantation of the programs with the incidence of the disease and the mortality rate.

The results of the study are reflected in the table on the right where the increase in cancer incidence is observed according to the implementation of the screening programs. For example, 40% of implantation (to the left of the graph) would be equivalent to an incidence of 200 cases per 100,000 women, while at the other end, 80% of implantation would cause double the incidence. Note, surprisingly, in the lower part, in red, that the higher incidence is not accompanied by any reduction in specific mortality.

If you take the time to read the article, you will see, in more specific graphs, that the increase in incidence is mainly due to tumours of small size (<2 cms). All this, the authors conclude, suggests that breast cancer preventive programs lead to overdiagnosis. That is, many small tumours (probably DCIS) appear despite the fact these would have had an indolent evolution.

Experts warn that there is already enough data to enable the managers responsible for breast cancer prevention to consider at least two actions: a) to warn women of the risks of overdiagnosis, and b) to restrictively review the criteria that delimit target populations for early detection of breast cancer.

Jordi Varela

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