Photo/Illutration Breast cancer tissue (Provided by Kyoto University)

Scientists discovered the cancer-causing cell with a genetic mutation that causes a common variant of breast cancer first emerges in patients around the age of puberty. 

A team of researchers primarily from Kyoto University, Tokyo Medical and Dental University and Keio University said the starter cell then undergoes repeated mutations, resulting in the onset of the carcinoma dozens of years later.

“One challenge still to overcome is solving the mystery as to why some cells can remain healthy despite the presence of the cancer-causing mutation,” said Seishi Ogawa, a tumor biology professor at Kyoto University, who was part of the research team.

He added, “Doing so will lead to the creation of technologies to predict cancer development risks and check patients more efficiently. That will contribute to the improved prevention and therapy of breast cancer.”

A breast tumor is the most frequently reported type of cancer for women. The variant in question accounts for 20 percent of all breast carcinoma cases.

The findings are expected to provide clues to developing methods to prevent breast cancer and enable earlier detection. 

Cancer is thought to develop when tumor cells, which are formed by genetic mutations accumulating in healthy cells, proliferate.

But when the original mutation transpires was unknown. How the first alteration ends up causing carcinoma in the cancer-generation processes was unclear, too.

The team relied on genome analysis to measure the speed of mutation accumulation.

Surveying the number of genetic alterations and the accumulation rate can determine their timing and order because mutations are inherited through cells’ division and proliferation.

Cancer cells were compared with their surrounding counterparts in five premenopausal breast cancer patients so the mutation processes could be sorted in chronological order.

The results revealed that four of them had a unique alteration found in 20 percent of breast carcinoma instances. Their mutation is projected to have occurred at the average age of 10.6 years.

The mutated cell started proliferating and spreading in tandem with the mammary glands’ development at the beginning of menstruation. New alterations transpired at the same time.

By the time the person turned around 30, multiple cells are estimated to have been on the verge of becoming tumorous. These patients were diagnosed as having cancer when they were between the ages of 41 and 48.

Looking into an additional five breast cancer patients with the same variety of mutations who were diagnosed at ages 53 through 75 during their postmenopausal periods, the scientists realized their alteration likewise occurred around their puberty years. 

The team’s findings were published on July 26 on the online edition of the British scientific journal Nature at (https://doi.org/10.1038/s41586-023-06333-9).

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