​​​​​​​ISTANBUL

A recent study revealed that high-dose radiotherapy may paradoxically worsen cancer by promoting metastasis of tumors, the South China Morning Post reported Wednesday.

Metastasis is the spread of cancer cells from the original tumor to other parts of the body via the bloodstream or lymphatic system, which makes treating the disease considerably harder.

Researchers led by biochemist Yang Kaiting at the University of Chicago Medicine Comprehensive Cancer Centre revealed the groundbreaking findings in the peer-reviewed scientific journal Nature.

In theory, radiotherapy should prevent the growth and spreading of tumors. But the research team discovered that some metastatic lesions that were not treated showed signs of growth after receiving high-dose radiation therapy.

Researchers analyzed biopsy samples from 22 tumor patients who received high doses of stereotactic body radiation therapy, covering various histological types.

Results showed that metastatic lesion volumes increased after treatment, suggesting that radiation therapy could promote tumor growth.

Further analysis of tumor biopsies showed changes in gene expression before and after radiotherapy. In patients who received the treatment, the gene for amphiregulin, a protein that activates key cellular pathways, was significantly elevated.

Amphiregulin binds to the epidermal growth factor receptor, influencing cell survival, growth, migration and death.

Researchers replicated the effect in mouse models of lung and breast cancer, finding that radiation increased amphiregulin production in tumor cells and serum, which boosted the growth of existing metastases while also reducing the growth of new ones.