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Simul Parikh: Time toxicity of treatment is real
Mar 31, 2024, 08:31

Simul Parikh: Time toxicity of treatment is real

Simul Parikh, Medical Director of OncoHealth, recently posted on LinkedIn:

“Time toxicity of treatment is real. An interesting example that comes up frequently in prior authorization for radiation oncology is the prescribing of > 10 fractions for bone metastases. This can be challenging for the doctor trying to treat their patient and also for the reviewer.

First of all, all the guidelines recommend against > 10 fractions – ASTRO, NCCN, and other groups all state that 1-10 fractions are recommended. Second, there are exactly zero studies showing > 10 fractions is superior to 10 fractions or less. There are nearly a few dozen comparing shorter to longer courses (usually 8/1 vs 20/5 or 30/10) and none show any benefit in pain control (duration, intensity). There are differences in re-treatment rates, but this is attributed to physicians not believing 8/1 works (i.e. – no metrics are different in the patient cohorts at the time of re-treatment). Thirdly, this is palliation, and bringing in patients for 2 weeks (10 fractions) is already a considerable cost on the patient’s remaining time in this world.

What do the doctors tell me when they ask for > 10 fractions? What are my suggestions?

‘They have radio-resistant disease’ – there are no studies showing any inherent benefit for higher doses for bone metastases in these cases. Consider going up on dose per fraction. We can safely give 10-12 Gy+/1 or 25 Gy/5 or 30 Gy/5. This may require conformal techniques (IMRT, SBRT).

‘They have a large tumor’ – again, no studies show difference in outcome with respect to size. If it is a concern, go higher dose/fraction.

‘They have a large soft tissue component’ – same answer; but, I do see the value in fractionation, and 10 fractions is reasonable. > 10 has no evidence.

‘It’s in ___ location and this will be less toxic’ – acute toxicity is determined by total dose, not dose/fraction. Many (but not all) of the SFRT vs MFRT studies show greater acute toxicity with fractionated courses. I presume going even longer would cause more of the same.

‘It’s the only site of disease/it’s oligometastic’ – well, then don’t do a palliative dose like 37.5 Gy in 15 Fx. Use IMRT/SBRT and give 24/2 or 30/5 or something like that. If you are aiming to control the cancer, you’ll have to give a higher BED.

Personally, I don’t make any patient come in for 2 weeks for bone met palliation. The data is the data and 1-5 fx works just as well for pain control. That being said, 10 fx is a standard. If the goal is different (ablation, consolidation of oligometastatic disease), then use the right tool – 40 Gy in 20 Fx is not it.

Let’s be mindful of time toxicity for these patients. Aim for treatment to be completed in a week or less.”

Source: Simul Parikh/LinkedIn