Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
2003-4-15
pubmed:abstractText
Information concerning radiation-induced malignancies comes from the A-bomb survivors and from medically exposed individuals, including second cancers in radiation therapy patients. The A-bomb survivors show an excess incidence of carcinomas in tissues such as the gastrointestinal tract, breast, thyroid, and bladder, which is linear with dose up to about 2.5 Sv. There is great uncertainty concerning the dose-response relationship for radiation-induced carcinogenesis at higher doses. Some animal and human data suggest a decrease at higher doses, usually attributed to cell killing; other data suggest a plateau in dose. Radiotherapy patients also show an excess incidence of carcinomas, often in sites remote from the treatment fields; in addition there is an excess incidence of sarcomas in the heavily irradiated in-field tissues. The transition from conventional radiotherapy to three-dimensional conformal radiation therapy (3D-CRT) involves a reduction in the volume of normal tissues receiving a high dose, with an increase in dose to the target volume that includes the tumor and a limited amount of normal tissue. One might expect a decrease in the number of sarcomas induced and also (less certain) a small decrease in the number of carcinomas. All around, a good thing. By contrast, the move from 3D-CRT to intensity-modulated radiation therapy (IMRT) involves more fields, and the dose-volume histograms show that, as a consequence, a larger volume of normal tissue is exposed to lower doses. In addition, the number of monitor units is increased by a factor of 2 to 3, increasing the total body exposure, due to leakage radiation. Both factors will tend to increase the risk of second cancers. Altogether, IMRT is likely to almost double the incidence of second malignancies compared with conventional radiotherapy from about 1% to 1.75% for patients surviving 10 years. The numbers may be larger for longer survival (or for younger patients), but the ratio should remain the same.
pubmed:grant
pubmed:commentsCorrections
pubmed:keyword
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0360-3016
pubmed:author
pubmed:issnType
Print
pubmed:day
1
pubmed:volume
56
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
83-8
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed-meshheading:12694826-Adenocarcinoma, pubmed-meshheading:12694826-Animals, pubmed-meshheading:12694826-Carcinoma, pubmed-meshheading:12694826-Dose-Response Relationship, Radiation, pubmed-meshheading:12694826-Female, pubmed-meshheading:12694826-Humans, pubmed-meshheading:12694826-Incidence, pubmed-meshheading:12694826-Leukemia, Radiation-Induced, pubmed-meshheading:12694826-Male, pubmed-meshheading:12694826-Neoplasms, Experimental, pubmed-meshheading:12694826-Neoplasms, Radiation-Induced, pubmed-meshheading:12694826-Neoplasms, Second Primary, pubmed-meshheading:12694826-Nuclear Warfare, pubmed-meshheading:12694826-Prostatic Neoplasms, pubmed-meshheading:12694826-Radiation Injuries, Experimental, pubmed-meshheading:12694826-Radiotherapy, Conformal, pubmed-meshheading:12694826-Radiotherapy, High-Energy, pubmed-meshheading:12694826-Radiotherapy Dosage, pubmed-meshheading:12694826-Risk, pubmed-meshheading:12694826-Sarcoma, pubmed-meshheading:12694826-Survivors, pubmed-meshheading:12694826-Uterine Cervical Neoplasms
pubmed:year
2003
pubmed:articleTitle
Radiation-induced second cancers: the impact of 3D-CRT and IMRT.
pubmed:affiliation
Center for Radiological Research, Columbia University, College of Physicians and Surgeons, New York, NY 10032, USA. ejh1@columbia.edu
pubmed:publicationType
Journal Article, Comparative Study, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S., Review