Screening for irradiation vasculopathy by intima-media thickness sonography in head and neck cancer patients.

PURPOSE: Post-irradiation vasculopathy is a severe form of atherosclerosis and affects the prognosis of head and neck cancer survivors. Sonographic intima-media thickness (IMT) precedes stenosis, plaque formation, and cerebrovascular events. Therefore, IMT may be a valuable screening marker for post-irradiation toxicity. However, the critical irradiation dose and the onset of IMT increase remain unclear. METHODS: The cross-sectional study analysed the carotid artery IMT in 96 irradiated patients and 41 controls regarding irradiation dose, post-irradiation-interval, and cardiovascular risk factors. Distinct irradiation doses to the tumour side and the contralateral hemineck enabled detection of dose depended effects within one patient and control of risk factors. RESULTS: Radiotherapy caused a dose-dependent increase in IMT. The toxicity did not have saturation effects for > 60 Gy. The IMT increase occurred in short-term following radiotherapy and the risk for a pathological value (> 0.9 mm) rose significantly. The correlation between IMT and radiotherapy was comparable to established cardiovascular risk factors. CONCLUSION: Radiotherapists should consider the additional toxicity of high doses for non-metastatic head and neck cancer. If neck metastases require radiotherapy with boost, IMT measurement is suitable for early detection of carotid artery damage.

Exposure of remote organs and associated cancer risks from tangential and multi-field breast cancer radiotherapy.

PURPOSE: With the ever-increasing cure rates in breast cancer, radiotherapy-induced cancers have become an important issue. This study aimed to estimate secondary cancer risks for different treatment techniques, taking into account organs throughout the body. MATERIAL AND METHODS: Organ doses were evaluated for a tangential three-dimensional conformal (3D-CRT) and a multi-field intensity-modulated radiotherapy (IMRT) plan using a validated, Monte Carlo-based treatment planning system. Effects of wedges and of forward versus inverse planning were systematically investigated on the basis of phantom measurements. Organ-specific cancer risks were estimated using risk coefficients derived from radiotherapy patients or from the atomic bomb survivors. RESULTS: In the 3D-CRT plan, mean organ doses could be kept below 1 Gy for more remote organs than the lung, heart, and contralateral breast, and decreased to a few cGy for organs in the lower torso. Multi-field IMRT led to considerably higher mean doses in organs at risk, the difference being higher than 50% for many organs. Likewise, the peripheral radiation burden was increased by external wedges. No difference was observed for forward versus inverse planning. Despite the lower doses, the total estimated secondary cancer risk in more remote organs was comparable to that in the lung or the contralateral breast. For multi-field IMRT it was 75% higher than for 3D-CRT without external wedges. CONCLUSION: Remote organs are important for assessment of radiation-induced cancer risk. Remote doses can be reduced effectively by application of a tangential field configuration and a linear accelerator set-up with low head scatter radiation.