Gene profiling can show which patients can avoid radiotherapy after breast cancer surgery

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Breast during mammography
Photographer: Johanna Ewald St Michaels

New research from Sahlgrenska Academy and Sahlgrenska University Hospital shows that precision medicine can identify breast cancer patient groups where radiotherapy after breast conserving surgery is not needed.

In three independent clinical trials, the POLAR specific gene profile showed which patients would benefit from local radiation therapy. Which in turn means that a specific group of breast cancer patients do not need to undergo radiation treatment, and thus can avoid possible side effects.

- The data show that patients with a low value of the POLAR gene profile has a equally low risk of local recurrence as those receiving radiotherapy. As treatment can have negative side effects, it is important to clinically determine and identify patients where radiotherapy is not needed, says Per Karlsson, professor of oncology at Sahlgrenska Comprehensive Cancer Centre.

Most patients who have undergone surgery in connection with breast cancer are recommended radiotherapy. And although only a small proportion of patients experience serious side effects from radiation, the total is quite a large number of patients considering how common breast cancer is. This type of gene profiling in conjunction with treatment can therefore improve the quality of life for many patients.

- The development of POLAR will need further validation and safety tests before it can be used in clinical work, emphasizes Per Karlsson.

About the study

In a study with principal investigators from Sahlgrenska Academy and Sahlgrenska University Hospital, a gene profile called POLAR (Profile for the Omission of Local Adjuvant Radiotherapy) has been developed that identifies when radiation treatment can be omitted.

The POLAR gene profile includes 16 genes that, among other things, control functions within the immune system and cell division rate. Meta-analysis of the three randomized trials confirms that the POLAR gene profile can identify patients in whom radiotherapy is not needed.

A team of researchers from Sweden, Scotland and Canada performed validation analyzes of 623 patients who participated in one of three randomized clinical trials, examining the effectiveness of breast-conserving surgery with and without local radiation therapy.

By studying the expression of different genes in the breast tumors in clinical trials where patients were randomized to radiotherapy or not, patients with breast cancer type who do not need radiotherapy after breast conserving surgery have been able to be identified.

The results of the trial study were presented by Per Karlsson, professor of oncology at the Sahlgrenska Comprehensive Cancer Center, at the San Antonio Breast Cancer Symposium on December 9.

All cancer care at Sahlgrenska University Hospital is gathered in the Sahlgrenska Comprehensive Cancer Centre. Being an accredited Comprehensive Cancer Center means that Sahlgrenska University Hospital meets European quality standards in terms of treatment, prevention, diagnosis, treatment, rehabilitation as well as research, teaching and training. The goal is to collaborate with the highest possible clinical competence and with research at the forefront to be able to provide patients with the best possible care.

The article was originally published in December 2022 at Sahlgrenskaliv.