Split course

It is a set of fractions planned and prescribed as a whole with a period of no treatment during them [1]. Split-course radiation therapy is an altered fractionation regimen originally designed to diminish radiation morbidity by splitting the total dose into at least two separate courses with an interruption of 10 to 14 days [2]. It allows  the body recovers while the cancer shrinks [3]. It may be disadvantageous compared with continuous treatment because the decreased radiation morbidity of normal tissues will also result in lower anti-tumour efficiency and reduced local control rates. There is also concern about repopulation during the rest period [4]. There are at least three regimens of split-course radiotherapy [5]:

1. Standard total treatment dose at 1.8 to 2.0 Gy fraction size, but with different total treatment time and an interruption interval of one to two weeks;
2. Standard total treatment dose but different fraction size to maintain the same overall treatment time including the interruption interval of one to two weeks;
3. Different total treatment dose, fraction size, overall treatment time and interruption interval.

Bibliographic references:
[1] Datadictionary.nhs.uk. (2016). Supporting Information: Radiotherapy Treatment Course. [online] Available at: http://www.datadictionary.nhs.uk/data_dictionary/nhs_business_definitions/r/radiotherapy_treatment_course_de.asp?shownav=1 [Accessed 2 Jun. 2016].

[2] Scanlon TW. Split dose radiotherapy: the original premise. Int J Radiat Oncol Biol Phys 1980;6:527-8. Available at: http://dx.doi.org/10.1016/0360-3016(80)90072-3.

[3] Cancer.org. (2015). External radiation therapy. [online] Available at: http://www.cancer.org/treatment/treatmentsandsideeffects/treatmenttypes/radiation/understandingradiationtherapyaguideforpatientsandfamilies/understanding-radiation-therapy-external-radiation-therapy [Accessed 2 Jun. 2016].

[4] Parsons JT, Bova FJ, Million RR. A re-evaluation of split-course technique for squamous cell carcinoma of the head and neck. Int J Radiat Oncol Biol Phys 1980;6:1645-52. Available at: http://dx.doi.org/10.1016/0360-3016(80)90246-1.

[5] Members of the Lung Cancer Disease Site Group. Altered fractionation of radical radiation therapy in the management of unresectable non-small cell lung cancer. Toronto (ON): Cancer Care Ontario; 2002 Sep [Endorsed 2012 Nov]. Program in Evidencebased Care Practice Guideline Report No.: 7-12 Version 2. Available at: https://www.cancercare.on.ca/common/pages/UserFile.aspx?fileId=14170 [Accessed 2 Jun. 2016].