Late complications are fortunately a very uncommon, even rare event after post-operative radiotherapy to the breast or the chest wall. Nonetheless, it underlies the importance of careful selection of only patients that will benefit from radiotherapy to undergo this treatment.
On the average, late complications happens many years after the course of radiotherapy and is generally unpredictable and is likely permanent in the patients having them.
Again, these late complications are related to the exposure of the surrounding normal tissues to radiation. These structures includes the skin of the breast, the breast itself, the underling lungs and heart (only when treating left-sided disease) and the ribs.
The breast sometimes becomes a little bit smaller and firmer in consistency. The colour of the skin may become more uneven. Occasionally, clusters of tiny blood vessels may be apparent especially in fair skinned patients. This is call telangiectasia. Other than affecting the cosmesis, these changes do not cause physical discomfort. This happens in less than 5% of patients.
Long term complications of the heart and lungs with the use of modern radiotherapy techniques is very much rarer than it used to be.
The underlying ribs are also exposed to radiation. With an increased risk of osteoporosis when the patients ages, these previously irradiated ribs may become even more fragile. The usually preventive measure taken for osteoporosis is helpful in keeping these risks to the minimum!
Limb swelling from the blockage of the lymphatic system can occur after surgery or radiation. With careful patient selection and careful radiation planning, the rates of lymphoedema is low in a modern cohort.
Although uncommon, patients should be aware that radiation is itself a carcinogen. i.e. it can cause cancer. Fortunately, the sum total of the risks of cancer attributable to radiation in cancer survivors is much less than the background risk of cancer in any one person. Certainly, it is very much lower compared to the very real threat of cancer recurrence which radiation prevents in a very effective, efficient and safe way.