Why does breast cancer reproduce? New study finds clues

TOKYO, Japan (AFP) – For breast cancer survivors, the risk of recurrence of the tumor is ubiquitous, with the possibility of recurrence up to two decades after diagnosis. But new research could help identify and treat those most at risk.

Doctors have traditionally relied on factors such as the size and grade of a tumor when diagnosed, the lymph node involvement and the age of the patient to determine the risk of relapse.

But the rate of recurrence of breast cancer and the reason why it persists remain "misunderstood", according to a study published Thursday in the journal Nature.

To address this situation, researchers used data from more than 3,000 breast cancer patients diagnosed in the UK and Canada between 1977 and 2005.

Nearly 2,000 of the cases included molecular cancer data that provided researchers with detailed information about tumors.

The data was used to develop a computer model that identified four subgroups with "an extremely high risk of late and distant relapse," said lead author Christina Curtis, assistant professor of medicine and genetics at the University of Toronto. Stanford University.

"These are the patients who are likely to experience a relapse after the initial diagnosis," she told AFP.

The study found that about 25% of women with the most commonly diagnosed form of breast cancer were between 42% and 55% at risk of seeing their cancer return in the next 20 years.

"These are the women who seem cured but then present with systemic disease many years later," Curtis said in a press release issued by Stanford University.

"Until now, there was no effective way to identify this subgroup of women likely to benefit from ongoing screening or treatment."

The study also opens up potential new pathways for further treatment of breast cancer patients by identifying gene alterations in each of the four subgroups at risk.

These alterations or mutations lead to signaling problems that can cause unwanted cell growth. And this can in turn fuel the formation of tumors or their progression.

"Many of these genomic modifications may be potentially therapeutically-targeted, suggesting the possibility of new treatment options, although this will need to be evaluated in the context of clinical trials," Curtis said at the same time. AFP.

The study also reveals when and where in the body breast cancers could metastasize and revealed a group of patients with a so-called triple negative tumor whose cancers are unlikely to reappear after five years.

"This information can be used to refine risk estimates and improve the follow-up and stratification of breast cancer patients – for example, by determining which patients might benefit from a longer or different type of treatment", said Curtis.

The researchers cautioned that their dataset included cases from several decades ago, which means that patients were not then able to access newer and more recent treatments. approved. Some of these treatments have significantly improved the survival rates of patients with particular types of breast cancer.

But the results should still significantly help physicians predict more precisely which patients are most at risk of seeing their cancer return.

The team even developed an online tool "predictor of breast cancer recurrence" for physicians using their model.

Curtis said the researchers are currently pursuing a clinical trial for treatment options that would target genomic defects in patients most at risk for cancer recurrence.