View source for Medicine:Prophylactic cranial irradiation

{{Infobox medical intervention |
  Name        = Prophylactic cranial irradiation |
  Image       = |[[File:Brain CT scan.jpg|250px]]
  Caption     = |
  ICD10       = |
  ICD9        = {{ICD9proc|92.21}} |
  MeshID      = |
  OPS301      = |
  Synonyms  = '''Prophylactic cranial radiotherapy''' |
}}

'''Prophylactic cranial irradiation''' ('''PCI''') is a technique used to combat the occurrence of [[Medicine:Metastasis|metastasis]] to the brain in highly aggressive [[Medicine:Cancer|cancer]]s that commonly metastasize to brain, most notably small-cell lung cancer.<ref>{{Cite journal|title = Decision analysis for prophylactic cranial irradiation for patients with small-cell lung cancer.|last = Lee|first = JJ|journal = J Clin Oncol|pmid = 16877726|pages = 3597–603|doi=10.1200/JCO.2006.06.0632|volume=24|issue = 22|date=Aug 2006|doi-access = free}}</ref>  Radiation therapy is commonly used to treat known tumor occurrence in the brain, either with highly precise [[Medicine:Stereotactic radiation therapy|stereotactic radiation]] or therapeutic cranial irradiation.  By contrast, PCI is intended as preemptive treatment in patients with no known current intracranial tumor, but with high likelihood for harboring occult microscopic disease and eventual occurrence.<ref>{{Cite web|url = http://www.xrt.upenn.edu/medical_student.shtml|title = Fundamentals of Radiation Oncology|access-date = 2014-08-30|website = Perelman School of Medicine|publisher = UPenn: Department of Radiation Oncology}}</ref>  For small-cell lung cancer with limited<ref>{{Cite journal|title = Risk of brain metastasis from small cell carcinoma of the lung related to length of survival and prophylactic irradiation|vauthors=Komaki R, Cox JD, Whitson W |date = 1981|journal = Cancer Treat Rep|volume = 65|issue = 9–10|pages = 811–4|pmid = 6268295}}</ref><ref>{{Cite journal|title = Prophylactic cranial irradiation for patients with small-cell lung cancer in complete remission. Prophylactic Cranial Irradiation Overview Collaborative Group|vauthors=Aupérin A, Arriagada R, Pignon JP |date = 1999|journal = NEJM|volume = 341|issue = 7|pages = 476–84|pmid=10441603|doi= 10.1056/NEJM199908123410703|display-authors=0|doi-access = free}}</ref> and select cases of extensive disease,<ref>{{Cite journal|title = Prophylactic cranial irradiation in extensive small-cell lung cancer|vauthors=Slotman B, Faivre-Finn C, Kramer G |date = 2007|journal = NEJM|volume = 357|issue = 7|pages = 664–672|doi=10.1056/nejmoa071780|pmid = 17699816|s2cid = 7086495|display-authors=0|doi-access = free}}</ref> PCI has shown to reduce recurrence of brain metastases and improve overall survival in complete remission.
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== History ==
During the fervor to develop treatments for pediatric leukemia in the 1960s, there was initial experimentation with PCI for children with [[Medicine:Acute lymphoblastic leukemia|ALL.]]  Although advances in [[Medicine:Chemotherapy|chemotherapy]] had been able to successfully treat tumor throughout the body, there remained an alarming incidence of brain metastasis following systemic chemotherapy. A theory was developed that the brain was likely a pharmacologic sanctuary where sub-clinical metastases were protected from cytotoxic drugs by the [[Biology:Blood–brain barrier|blood–brain barrier]].  Oncologists hypothesized that treatment of this sub-clinical disease with radiation therapy may stamp out the malignant process before it could advance to cause symptoms.  Indeed, subsequent studies showed that an increased rate of disease-free survival and overall survival in those children treated with PCI.  Due to successes with pediatric blood cancers, the concept of PCI was enlisted for the treatment of other types of cancers.

Over time, there has slowly been a shift away from PCI due to incidence of long-term side effects and secondary cancers, as well as evidence of equivalent control with alternate forms of treatment such as long-term intrathecal chemotherapy.<ref>{{Cite journal|title = CNS-directed therapy for childhood acute lymphoblastic leukemia: Childhood ALL Collaborative Group overview of 43 randomized trials|vauthors=Clarke M, Gaynon P, Hann I |date = 2003|journal = J Clin Oncol|volume = 21|issue=9 |pages = 1798–809|doi=10.1200/jco.2003.08.047|pmid=12721257 |display-authors=0}}</ref>  For ALL, PCI had been reserved only for high-risk cases; however, a 2009 study by Ching-Hon et al. reporting on the results of clinical trial NCT00137111 suggesting that PCI is unwarranted even in high-risk cases.<ref>{{Cite journal|title = Treating Childhood Acute Lymphoblastic Leukemia without Cranial Irradiation|last = Ching-Hon|date = Jun 25, 2009|journal = NEJM|volume = 360|issue = 26|pages = 2730–2741|doi=10.1056/NEJMoa0900386|display-authors=0|pmid=19553647|pmc=2754320}}</ref>   Despite changing recommendations for ALL, PCI continues to play an important role in treatment of small-cell lung cancer.

=== Dosing ===
Early trials for PCI in ALL utilized high-dose treatments, up to 24 Gy cumulative dose, that resulted in significant toxicity.  Further experiments showed that lower-dose treatments (12–18 Gy)<ref>{{Cite journal|title = Improved outcome in childhood acute lymphoblastic leukemia despite reduced use of anthracyclines and cranial radiotherapy: results of trial ALL-BFM 90. German-Austrian-Swiss ALL-BFM Study Group.|last = Schrappe|date = Jun 1, 2000|journal = Blood|pmid = 10828010|volume=95|issue = 11|pages=3310–22|display-authors=0}}</ref><ref>{{Cite journal|title = Excellent therapeutic efficacy and minimal late neurotoxicity in children treated with 18 grays of cranial radiation therapy for high-risk acute lymphoblastic leukemia: a 7-year follow-up study of the Dana-Farber Cancer Institute Consortium Protocol 87-01.|last = Waber|date = Jul 1, 2001|journal = Cancer|pmid = 11443604|volume = 92|issue = 1|pages = 15–22|doi=10.1002/1097-0142(20010701)92:1<15::aid-cncr1286>3.0.co;2-w|display-authors=0|doi-access = }}</ref> administered in smaller fractions provide equivalent benefit with lower neuro-toxicity.

==References==
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{{Radiation oncology}}

[[Category:Cancer treatments]]
[[Category:Oncology]]
[[Category:Medical treatments]]
[[Category:Radiation therapy]]

{{Sourceattribution|Prophylactic cranial irradiation}}