Refining existing prostate cancer treatments: radiotherapy timing
One of the main treatment options for prostate cancer is radiotherapy. This article, the sixth in my 30-article series to raise money for prostate cancer research during November, 2026, describes a fascinating example of the potential for progress in reducing the adverse effects of radiotherapy treatment.
Prostate cancer radiotherapy 101
The impressive collection of high tech equipment you see in the photo at the top of this article is a state-of-the-art radio therapy system configured for a prostate cancer patient. The horizontal unit is the 'bed' where the patient lies down, feet on the right, head on the left. This bed then slides to the left while the four large modules on the left rotate around the body to deliver the radio waves to the target, i.e. the prostate.
The idea is that accurately focused radio waves damage and kill cancer cells. That accuracy depends in part on the patient. I will go into more detail about all of this a future post, and I provide tips on meeting the rather exacting biological requirements for the patient. In crude terms: fill bladder, empty bowel, clear gas, lie very still.
Fortunately, each treatment session takes only a few minutes and they do not hurt. A typical course of treatment is 20 sessions performed on consecutive weekdays (mine went: Wed/Thu/Fri; Mon thru Fri; Mon thru Fri; Mon thru Fri; Mon/Tue).
Is there a "right time of day" for safer prostate cancer radiotherapy?
When I was going through my radiotherapy, in July of 2026, I found that meeting the biological requirements for morning appointments was easier than for those later in the day. I spoke to several fellow patients that felt the same way.
In fact most of my appointments were for 9:30 in the morning, but not all. The same equipment is used to treat a range of cancers in patients of all ages and genders and levels of health. Not everyone can walk in and hop up on the treatment bed. Also, the equipment is on strict maintenance schedules that take it offline.
Basically, prostate cancer radiotherapy is scheduled around practical questions: when is the machine available, when can the patient get to hospital, and how can the staff fit everyone in? But intriguing new research suggests another question may need to be added: what does the patient's body clock think is a good time?Researchers at the University of Leicester, working with European colleagues, have found evidence that the time of day at which prostate cancer patients receive radiotherapy may influence their chances of developing long-term side effects. (I will be talking about what those side effects are in a separate article.)
Crucially, the answer appears to depend on their genes. (As reported here.) The researchers used data from the international REQUITE study, which followed 1,760 men undergoing external-beam radiotherapy, the kind described above. For 877 of these men, researchers had sufficiently detailed information about treatment times, genetic variations and side effects over the following two years.
Researchers focused on variations in PER3, a gene involved in regulating circadian rhythms, that internal 24-hour clock which influences our sleep, hormone activity, and our body's ability to repair damaged cells. The findings were striking:
- For men carrying one particular PER3 variant, the researchers' model predicted that avoiding radiotherapy around midday could reduce the risk of subsequent urinary incontinence from 15% to 5%.
- For another genetic group, receiving treatment at 5pm rather than 9am was associated with a predicted reduction in rectal bleeding risk from 11% to 5%.
But apparently this is not a case of simply declaring afternoon appointments safer. Some genetic groups appeared to benefit from midday treatment, while others showed little effect from timing at all. There are also important caveats.
This was an observational study, not a clinical trial in which men were deliberately assigned different treatment times. The percentages are model-based predictions, not demonstrated improvements. Further research is required to establish whether adjusting appointment times actually reduces harm without affecting cancer control. (Full study published in Clinical Cancer Research.)
Despite tohse caveats, I find the implications fascinating. If the results hold up, a relatively simple genetic test could help hospitals allocate radiotherapy appointments according to patients' biological clocks. No new radiation machine, miracle drug or expensive treatment would be required, just a more "intelligent" timetable.
As someone who recently completed prostate radiotherapy, I find this a particularly appealing idea. The goal should not simply be to eradicate the cancer, but to minimise the price patients pay for surviving it. Kudos to all involved in this research!
P.S. My enthusiasm for this research has nothing to do with the fact that the University of Leicester is only 25 miles from where I live and also my alma mater (MSc in Security and Risk Management, School of Criminology, 2016).










