title: [The issue of low doses in radiation therapy and impact on radiation-induced secondary malignancies].
abstract: Several studies have well documented that the risk of secondary neoplasms is increasing among patients having received radiation therapy as part of their primary anticancer treatment. Most frequently, radiation-induced neoplasms occur in volume exposed to high doses. However, the impact of "low" doses (<5 Gy) in radiation-induced carcinogenesis should be clinically considered because modern techniques of intensity-modulated radiation therapy (IMRT) or stereotactic irradiation significantly increase tissue volumes receiving low doses. The risk inherent to these technologies remains uncertain and estimates closely depend on the chosen risk model. According to the (debated) linear no-threshold model, the risk of secondary neoplasms could be twice higher with IMRT, as compared to conformal radiation therapy. It seems that only proton therapy could decrease both high and low doses delivered to non-target volumes. Except for pediatric tumors, for which the unequivocal risk of second malignancies (much higher than in adults) should be taken into account, epidemiological data suggest that the risk of secondary cancer related to low doses could be very low, even negligible in some cases. However, clinical follow-up remains insufficient and a marginal increase in secondary tumors could counterbalance the benefit of a highly sophisticated irradiation technique. It therefore remains necessary to integrate the potential risk of new irradiation modalities in a risk-adapted strategy taking into account therapeutic objectives but also associated risk factors, such as age (essentially), chemotherapy, or life style.
authors.affiliation: Hôpital d'instruction des armées du Val-de-Grâce, service d'oncologie-radiothérapie, 75005 Paris, France, Institut Gustave-Roussy, Inserm 1030, radiothérapie moléculaire, 94805 Villejuif, France.
authors.forename: Cyrus
authors.initials: C
authors.lastname: Chargari
authors.affiliation: Institut Curie, département d'oncologie-radiothérapie, 75005 Paris, France, Hôpital privé des Peupliers, unité de radiothérapie, groupe Générale de Santé, 8, place de l'Abbé-Georges-Hénocque, 75013 Paris, France.
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Cosset
mesh_terms: D000328:Adult; D000367:Age Factors; D001943:Breast Neoplasms / Q000532:radiotherapy; D002648:Child; D005260:Female; D006689:Hodgkin Disease / Q000532:radiotherapy; D006801:Humans; D008297:Male; D009381:Neoplasms, Radiation-Induced / Q000517:prevention & control; D016609:Neoplasms, Second Primary / Q000209:etiology* / Q000517:prevention & control; D011471:Prostatic Neoplasms / Q000532:radiotherapy; D061766:Proton Therapy / Q000009:adverse effects*; D016634:Radiosurgery / Q000009:adverse effects*; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects*; D012306:Risk
keywords: intensity-modulated radiation therapy; irradiation; low doses; secondary neoplasms