- The radiation exposure of the heart has decreased in radiation therapy of breast cancer over the last years and thereby the risk of radiation induced cardiovascular diseases. The PASSOS heart study didn’t have enough observation time to provide significant evidence of the radiation risk and is thus going to be extended.
- Radiation techniques as well as concepts regarding the target volume have been refined during the term of the project. On the one hand, radiotherapy under deep inspiration has the potential to reduce the heart dose significantly. On the other hand, current studies show a reduction of recurrences when applying additional radiation to regional lymph nodes, which however means an additional radiation exposure to the surrounding organs. It is therefore necessary to extend the software by modern techniques, such as VMAT for example, or new fractionation schemes.
- The personalization can be further advanced: First, risk models can be extended by personal risk factors since new studies provide additional information and by improving the connection to studies on the baseline risk. Second, the spectrum of possible radiation techniques has been broadened, so that a patient-specific prediction of the dose with regards to the various techniques is more important than ever.
- Relative to the dose, the risk of second primary tumors after radiation therapy is lower than the radiation risk in cohorts of occupationally exposed people or in the survivors of the nuclear bombs of Hiroshima and Nagasaki. Modern studies on second primary tumors after radiation therapy provide information on the dose-response-relationship down to few gray. The discrepancy in the risk is not yet understood and probably cannot be attributed to cell sterilization at high doses only. The high dose area is restricted to a limited area close to the target volume for modern radiation techniques, so that risk assessments for the medium dose range are of utmost importance for the health risk. Mechanistic analyses can yield insights into these questions and can improve the risk assessments for organs with high dose gradients.
Intended further developments
A lot has been achieved in PASSOS but new challenges and questions have arisen. The project is terminated end of 2016; still, further developments keep being of high interest regarding the following areas: