IMRT in the treatment of head and neck cancer: is the present already the future?
Disease outcome in locally advanced head and neck cancer patients is far from satisfactory. The main causes of failure remain linked to locoregional recurrences, which are due to incomplete eradication of clonogenic cells. Conventional radiation therapy or 3-dimensional conformal radiation therapy are currently carried out at their extreme possibilities due to their intrinsic limitation--namely the impossibility to generate concave dose distributions without compromising tumor irradiation. Approximately a third of patients treated with radiotherapy and most head and neck cancer cases present concave shapes of the target volumes. With the advent of intensity modulated radiation therapy--clinically available for only few years--head and neck patients can now benefit from strategies based on highly conformal techniques. It is possible to exploit efficiently dose-escalation protocols to increase probabilities to eradicate clonogens, to reduce overall treatment time, to control repopulation problems and to keep as low as reasonably necessary the irradiation of healthy tissues minimizing acute and late complications. Today, both planning and clinical studies demonstrate these advantages but larger controlled trials are necessary to assess the true potentialities of techniques based on intensity modulation for head and neck cancers. In a speculative view, proton therapy, possibly with intensity modulation, or light ion therapy should be considered for selected cases or for reirradiation due to their higher biological efficacy and their degree of dose-conformation to target volumes.
Oncology Institute of Southern Switzerland, Radiation Oncology Department, Medical Physics Unit, Ospedale S. Giovanni CH-6504 Bellinzona, Switzerland. lucozzi@iosi.ch
Luca
L
Cozzi
Antonella
A
Fogliata
D002986:Clinical Trials as Topic; D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D007477:Ions / Q000627:therapeutic use; D010934:Planning Techniques; D061766:Proton Therapy; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000379:methods; D016896:Treatment Outcome
D007477:Ions