Radiation Oncology/Treatment time

This page discusses how the time from surgery, overall treatment time, and time to deliver a fraction have an impact on the success of treatment.

See also: the appropriate Radiobiology concepts.

The concept of surgery to radiotherapy interval (SRI):

The concept of overall treatment time:

Head & Neck

Aarhus, 2007 (Denmark) PMID 17493700 -- "Tumor progression in waiting time for radiotherapy in head and neck cancer." (Jensen AR, Radiother Oncol. 2007 Jul;84(1):5-10.)
- Retrospective. 61 patients with SCCHN, with diagnostic and treatment-planning CT scan. Median interval between scans 28 days (5-95)
- Outcome: 62% patients measurable increase in tumor volume; median increase 46% (6-495%). 20% new LN mets, 16% progression in T-stage
- Doubling time: median 99 days, but median for faster half was 30 days.
- Conclusion: Negative impact of waiting time; majority showed progression within 4 week waiting time
- Editorial PMID 17574695 -- "Killing time: The consequences of delays in radiotherapy." (Mackillop WJ, Radiother Oncol. 2007 Jul;84(1):1-4.)

Wisconsin; 2007 PMID 17305251 -- "Is there an optimum overall time for head and neck radiotherapy? A review, with new modelling." (Fowler JF, Clin Oncol (R Coll Radiol). 2007 Feb;19(1):8-22.)
- LQ modelling for various schedules, calculated tumor log cell kill, with acute and late complications
- Conclusion: Schedules of 4-6 weeks give 11 log10 cell kill; most require two fractions/day

Ontario, 1996 PMID 12118558 -- "The effect of delay in treatment on local control by radiotherapy." (Mackillop WJ, Int J Radiat Oncol Biol Phys. 1996 Jan 1;34(1):243-50.)
- Monte Carlo simulation, applied to tonsillar CA
- Outcome: at some point for every patient, probability of local control decreases sharply over a relatively short time period. LC rate decreases by ~10% per month for tonsillar CA
- Conclusion: Waiting times for RT should be As Short As Reasonably Achievable (ASARA)

Netherlands; 2003 PMID 14676792 -- "Accelerated regrowth of non-small-cell lung tumours after induction chemotherapy." (El Sharouni SY, Br J Cancer. 2003 Dec 15;89(12):2184-9.)
- Retrospective. 23 patients with NSCLC. Interval times between end of induction of start of RT evaluated. Mean time to RT 80 days
- Outcome: 41% potentially curable patients became incurable; tumor median doubling 29 days (8.3-171 days)
- Conclusion: Accelerated tumor cell proliferation, much shorter doubling time than for untreated tumors. Gain from chemo (tumor decrease) was lost with waiting for RT