MD, PhD, FMedSci, FRSB, FRCP, FRCPEd.

Acute radiation-induced proctitis (ARP) is a common side effect following radiotherapy for malignant pelvic disease. It occurs in about 75% of patients and often proves difficult to treat thus causing much pain and suffering. Aloe vera has been advocated for the prevention of ARP, but does it work?

This study evaluated the efficacy of Aloe vera ointment in prevention of ARP. Forty-two patients receiving external-beam radiotherapy (RT) for pelvic malignancies were randomized to receive either Aloe vera 3% or placebo topical ointment during radiotherapy for 6 weeks. Participants applied ointments especially manufactured for the study rectally via applicator, from the first day of starting radiotherapy for 6 weeks, 1 g twice daily. They were evaluated based on the severity (grade 0-4) of the following symptoms weekly: rectal bleeding, abdominal/rectal pain, diarrhoea, or faecal urgency. RTOG acute toxicity criteria and psychosocial status of the patients were also recorded weekly. Lifestyle impact of the symptoms, and quantitative measurement of C-reactive protein (CRP), an indicator of systemic inflammation, were also measured.

The results demonstrated a significant preventive effect for Aloe vera in occurrence of symptom index for diarrhoea (p < 0.001), rectal bleeding (p < 0.001), and faecal urgency (p = 0.001). The median lifestyle score improved significantly with Aloe vera during RT (p < 0.001). Intervention patients had a significant lower burden of systemic inflammation as the values for quantitative CRP decreased significantly over 6 weeks of follow-up (p = 0.009).

The authors concluded that Aloe vera topical ointment was effective in prevention of symptoms of ARP in patients undergoing RT for pelvic cancers.

This is by no means the first study of its kind. A previous trial had concluded that a substantial number of patients with radiation proctitis seem to benefit from therapy with Aloe vera 3% ointment. And another study has shown that the prophylactic use of Aloe vera reduces the intensity of radiation-induced dermatitis.

The new trial seems to be methodologically the best so far. Yet it is not perfect, for instance, its sample size is small. Therefore, it would probably be wise to insist on more compelling evidence before this approach can be recommended in oncological routine care.

9 Responses to Prevention of acute radiation-induced proctitis with Aloe vera

  • Edzard,

    Acute radiation-induced proctitis (ARP) is a common side effect following radiotherapy for malignant pelvic disease. It occurs in about 5% of patients and often proves difficult to treat thus causing much pain and suffering.

    I think you are confusing acute and chronic radiation proctitis, which are different problems. In general, radiotherapists worry much more about the latter, since late effects of radiation exposure (defined as beginning a year or more after exposure) do not, on the whole, get better, and often progress. Chronic radiation proctitis often presents with bleeding, which can be heavy and require regular blood transfusions. Other manifestations are incontinence, ulceration and fistulae, and of course pain. It is a very difficult problem to treat, and I was lucky enough to know a gastroenterologist at another cancer centre nearby (Dr Jervoise Andreyev) who had a special interest in radiation effects on the bowel, and who had developed protocols for investigation and treatment which helped many of my patients. He managed to get other gastroenterologists interested and indeed trained two of the consultants and my own centre in this little-known sub-speciality. Of course, prevention is much better than cure, and most of the progress in this area has been due to improvements in radiotherapy technique (such as intensity-modulated radiotherapy, image-guided radiotherapy and adaptive radiotherapy). When I retired there was a trial under way looking at the use of rectal obturators to push the rectal wall out of the treatment volume; there was also research into what made individual patients more sensitive, such as variations in lymphocyte function and defects in DNA repair mechanisms. One approach involved preventing bile salts from reaching the rectum, which seemed to be quite effective but not very practical.

    The article that you are reviewing was concerned only with acute radiation-induced proctitis, which is very common. According to the authors, this affects 75%), which I would think is about right. Acute proctitis is unpleasant, but self-limiting as it generally resolves within a few weeks (sometime months) of completing treatment. There are a number of approaches to minimising its impact, including diet and the use of topical steroids, but any other simple measures would be very welcome.

    In this study the difference in symptoms found between the aloe vera and the control group is impressive. Despite the small numbers, the magnitude of the effect is large, and I would have thought that other cancer centres would be interested in conducting larger-scale trials, particularly as rectal aloe vera is a cheap and simple intervention. I am surprised, therefore, that the authors chose to submit it to a complementary medicine journal and not to one that might be read by radiation oncologists.

    I see, though, that none of the authors are radiation oncologists, radiotherapy physicists or treatment / planning radiographers themselves, so perhaps the relevant journals might not figure on their radar, or conversely, might not have taken them seriously. Certainly there are a number of things that I would have liked them to have addressed in this paper.

    I think the most important thing would be more details of the radiotherapy received. They report some sort of average total dose of radiation received in the two groups without any explanation of what they mean by this and without distinguishing between regimens using 2.0Gy and 1.8Gy per fraction, which are radiobiologically different. Presumably this was the prescribed dose, which is still meaningless without specifying where it was prescribed to (the centre of the tumour? the maximum dose point? the minimum dose to a defined proportion of the treatment volume…). However, what actually matters is not what was prescribed to the tumour, but what was received by the rectum. This information can be readily obtained from the radiotherapy treatment plan since the rectum (being an organ at risk) is routinely defined as a three dimensional structure and the planning system generates a curve showing what proportion of it receives what dose. As a very miniminum they should have given some indication of how this differed between the treatment and the control groups

    Nor does there seem to have been any stratification by radiotherapy technique used; they do give some details of treatment for early prostate cancer, locally advanced prostate cancer, cervical cancer and bladder cancer, from which it is clear that the rectal dose distribution would be quite different in each case. If the treatments were not matched between the aloe vera and the control group this would be enough to skew the results, particularly given the small numbers (it is possible to infer, from the differing sex ratios, that the aloe vera group contained more people small-volume treatments to the pelvis and the control group contained more people have whole pelvis treatments for cervical cancer “plus a boost”, which probably meant the insertion of a radiation source into the uterus and which can sometimes produce a hot spot in the rectum).

    I would also comment that the radiotherapy techniques used seem to be at least 15 years out of date (at least in comparison to the UK). The use of personalised blocks to shield the rectum suggests that they did not have a linear accelerator equipped with a multi-leaf collimator, which would have limited the flexibility of conformal radiotherapy and procluded intensity-modulated radiotherapy and other modern developments altogether. I note that the centre was in Iran and I appreciate that they may not have had the advantages that we enjoy in the UK.

    Interestingly, the authors list some of the clinical features of their patients, several of which (diabetes, previous pelvic surgery) are risk factors for proctitis and were present in more of the control group.

    So on balance this is an interesting study, which certainly deserves to be repeated, but this time with some input from a radiotherapist. I would also want a longer follow-up period to see whether aloe vera has any effect on the risk of chronic radiation proctitis; this would require greater numbers, of course, as it is a much less common problem.

  • I’m reminded of the old claim that aloe vera promotes wound healing. When I was a kid, I did a crude test — treated half of a deep scratch with aloe vera (raw goop squeezed straight from the handy houseplant) and covered the wound with a bandaid. The treated half took about 3x longer to heal. Considered it debunked and thought no more about it.

    Fast-forward to a couple decades ago when someone tested this experimentally, using the same technique but a larger sample. Same result — aloe vera actually *slowed* wound healing, by roughly a factor of three.

    However, this makes it useful for treating burns, where you want healing to go slow so you get fewer bad scars.

    • Sandra

      Ignoring the very poor methodology of both trials, I could see no mention of homeopathic calendula in either of them. It seemed to be a straightforward calendula extract in both cases.

  • @EE

    Edzard, you must be slipping in your old age … no ?
    I thought your referred to that type of evidence as anecdote ? …. hmmm… double standards again.

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