Genomic Tests for Radiation Suitability

Did you know there is a genomic test to assess potential radiation side-effects?

Genomic science can now solve the puzzle of why some cancer patients experience worse radiation side effects

Patient’s Experience of Radiation Therapy:

There is no doubt that for some patients’ radiation therapy is lifesaving and life extending, however side effects – both short and long term, can cause cancer patients significant suffering. The impact of life changing side effects can impact physical and psychological wellbeing. Side effects such as discussed on this page, especially in cancer patients over 60 years of age, should be taken into account. Short or long term debilitation may be able to be avoided. 
Therefore, in 2020; when other choices of radiation types and more targeted radiation therapies are available; it makes sense that if radiation has been prescribed for you; to take a simple test to see if you harbour variants in your TGFβ1 gene; the gene vaiant that is responsible for radiation fibrosis.

Why test? What is Radiation-Induced Fibrosis (RIF)?

Radiation-induced fibrosis (RIF) is a long-term side effect of external beam radiation therapy for the treatment of cancer.  RIF usually appears 4 – 12 months after radiation therapy and may progress over several years.

 The clinical presentation depends on the type of tissue exposed to irradiation. The development of RIF can be described as a “wound-healing response gone wrong”, and may manifest as skin induration and thickening, muscle shortening and atrophy, limited joint mobility, lymphedema, mucosal fibrosis, ulceration, fistula, hollow organ stenosis and pain – all of which can significantly impact a patient’s quality of life. 

Did you know that the TGFβ1 gene variation is associated with a low or high risk of developing radiation fibrosis? You can now be tested!

What causes Radiation-Induced Fibrosis?

There have been several studies that suggest the radio-sensitivity of the breast is determined by genetic factors. The C−509T TGFβ1 variant allele may be used as a genetic marker to identify patients at elevated risk for fibrosis following radiotherapy.

Transforming growth factor-b1 (TGFβ1) is the major cytokine responsible for the regulation of fibroblast proliferation and differentiation. (Cytokines are small secreted proteins released by cells have a specific effect on the interactions and communications between cells). It has been suggested that an increase in these fibroblasts may trigger the development of fibrosis.

Radiation induces long-term TGFβ1 overexpression due to oxidative stress and an inflammatory response.  Elevated serum TGFβ1 levels were correlated with an increased risk of fibrosis in breast and lung cancer patients.

This has been genetically associated with variants in the TGFβ1 gene. This “gene” knowledge empowers cancer patients who are considering radiation therapy; thereby making a more informed choice and exploring different types of radiation therapy. Genomic tests can reveal if you have variants in your TGFβ1 gene.

Why would I consider Radiation Sensitivity testing?

Genomic Testing can determine if you have the TGFβ1 genetic variation which may be associated with low or high risk of developing fibrosis.

Around 50% of patients with solid malignant tumours receive radiation therapy at some point in the course of their disease.

For women with early-stage breast cancer, breast-conserving therapy involving breast-conserving surgery followed by whole-breast irradiation and optionally a boost to the tumour bed, is a standard therapeutic option.

A boost to the tumour bed means that an extra dose of radiation is applied that covers the initial tumour site. A boost of radiotherapy to the tumour bed is commonly used as a local recurrence occurs mostly at the site of the primary tumour because remaining microscopic tumour cells are most likely situated there; and radiation can eliminate these microscopic tumour cells.

Knowing whether you may have a low or high risk of developing fibrosis can be helpful when deciding whether to give a tumour bed boost after whole-breast radiation, as a boost may increase the risk of fibrosis while modestly decreasing recurrence risk.