Aloe Vera for Preventing Radiation-induced Skin Reactions: A Systematic Literature Review

Abstract

Aim

To systematically review and critically appraise the evidence for effectiveness of Aloe vera gel for radiation-induced skin reactions.

Materials and methods

Major biomedical databases and specialist complementary and alternative medicine databases were searched. Additionally, efforts were made to identify unpublished and ongoing research. Relevant research was systematically categorised by study type and appraised according to study design. Clinical commentaries were obtained for each study included in the review.

Results

One earlier systematic review on Aloe vera for a variety of conditions was located. Five published randomised-controlled trials (RCTs) were found, along with two additional RCTs that are not published. No non-RCTs, uncontrolled studies or qualitative studies were found.

Conclusions

There is no evidence from clinical trials to suggest that topical Aloe vera is effective in preventing or minimising radiation-induced skin reactions in cancer patients. Further methodologically rigorous, sufficiently powered research studies should be conducted to evaluate the effectiveness of currently used and novel therapies for the prevention, minimisation and management of radiation-induced skin reactions.

Introduction

Radiation-induced skin reactions remain a common adverse effect of radiotherapy treatment for cancer, despite the introduction of sophisticated skin-sparing techniques. Concomitant chemotherapy and radiotherapy can further increase the risk of an adverse reaction [1]. Estimations of the extent of skin reactions experienced by women undergoing radiotherapy for breast cancer range from 87% to 96% 2, 3.

Reactions vary from mild erythema to moist desquamation [2]. The reported incidence of moist desquamation is, however, relatively low (10–15%) 1, 3. Severity of skin reaction depends on a number of factors, including radiation fractionation, total dose, anatomic treatment area, radiation energy and individual patient differences, such as obesity and smoking habits 4, 5, 6. Archambeau et al. [7] report that skin damage has a dose–response relationship, starting at 20–25 Gy. In practice, this means that skin reactions occur around the second to third week of radical radiotherapy, reaching a peak towards the end of treatment 8, 9. Skin reactions can cause pain and discomfort, and may be dose-limiting 10, 11. General skin care advice, such as washing and avoidance of friction and trauma, are recommended [1]. The patient experience of symptom distress associated with radiation treatment is, however, an area that has been poorly researched [1].

The management of skin reactions across the UK has previously been reported to be inconsistent 12, 13, 14. Guidelines produced by NHS Quality Improvement Scotland [15] advise that only skin-care products advocated by the radiotherapy treatment centre should be applied. In 1995, a survey reported that 50% of the Radiation Therapy Oncology Group (RTOG) institutions used Aloe vera gel as a routine treatment [2]. However, Aloe vera does not feature in current practice guidelines [15]. Wells and MacBride [1] suggest that creams with active and moisturising ingredients may prevent the onset and severity of erythema, but indicate that more research is necessary (p. 156).

According to Murray and Pizzorno [16], more than 300 species of Aloe vera plants exist, the most popular medical variety being Aloe vera. The nomenclature of Aloe vera is confusing because the plant is known by a variety of names, most notably Aloe babadensis and Aloe vulgari. Furthermore, the geographical origin of the plant is unclear. Historical records indicate that it may have originated from Egypt or the Middle East, but Aloe has been introduced throughout the tropics and warmer regions of the world. Aloe vera gel should not be confused with aloe juice or latex, which is obtained from the same plant. Aloe gel is a clear jelly-like substance that is obtained from the thin-walled sticky cells of the inner portion of the leaf. Aloe latex (or juice) is obtained from the cells beneath the plant's skin, and contains laxative anthraquinones [17].

Aloe vera is commonly used to treat a number of skin complaints, such as dry skin and irritant contact dermatitis [18], and for the healing of burns [19]. The use of Aloe vera in the treatment of radiation-induced dermatitis has been reported in the literature as early as 1935 [20]. Aloe vera gel has also been assessed as a treatment for radiation-induced mucositis [21]; Klein and Penneys [22] suggest that studies and case reports provide support for the use of Aloe vera in the treatment of radiation ulcers and stasis ulcers in humans. Furthermore, Aloe vera as a tincture has also been researched as a treatment for cancer progression [23].