What are the risks of conventional irradiation?

In the case of conventional (photon) irradiation, the patient is exposed to excessive irradiation of the healthy tissues. This poses a risk of late and very late toxicity. This means, in the long term, that the consequences of unwanted radiation delivered to the healthy tissues and organs, such as such damage to the heart or lungs or secondary tumors, are often manifested long after the end of treatment.

• Undesired irradiation of the heart, lungs and spinal cord may occur during the treatment of breast cancer. These organs are very sensitive to radiation, even at low doses, and their damage can have significant side effects. This is especially true for tumors located in the left breast. Due to proximity of the heart, there is an increased risk of heart exposure.
• Breast cancer can spread to the lymph nodes in the armpit. In such cases, radiation is delivered not only to the breast or chest wall, but also to the armpits and areas behind the collarbone. With such irradiation, the exposure to heart and lungs is higher.
• Due to increasing chances of survival in breast cancer patients, there is a growing concern about long-term side effects of irradiation. In many cases, long-term side effects of irradiation may have a significant impact on the quality of life. 

For protons, there is no need to compromise, as proton therapy allows irradiation of the entire area, while allowing to reduce the dose to the heart and lungs about ten times.

Drawbacks and risks of conventional photon IRRADIATION

• Heart diseases from irradiation – ischemic heart disease, arrhythmia
• Pulmonary toxicity – development of pulmonary fibrosis
• Secondary tumors from radiation
• Reduced radiation doses as a compromise between efficacy and safety = insufficient treatment of the tumor

Manifestations of side effects many years after the treatment.