Aloe as a chemotherapy adjunct
Cancer will cause an estimated 585,720 deaths in 2014, and 1,665,540 new cases will be diagnosed this year.1 In addition to standard therapies, many patients with cancer use complementary therapies such as glutamine, fish oil, green tea, milk thistle, and curcumin. Aloe has also been evaluated for a potential adjunctive role in cancer therapy.
The genus Aloe, containing more than 400 plants, is used topically to treat sunburns and to accelerate wound healing. Oral aloe is used for osteoarthritis and ulcerative colitis as well as for cancer. In addition to antiproliferative and antioxidant effects, aloe may possess immunostimulatory activity due to acemannan, a mucopolysaccharide that stimulates macrophage activity.
An in vivo study showed that macrophages treated with acemannan resulted in an induction of interleukin-6 and tumor necrosis factor–alpha. The antiproliferative effects have been attributed to aloe-emodin, aloesin, and aloin, compounds that have been shown in vitro and in vivo to induce apoptosis in multiple cell lines. Polyphenols and other reactive oxygen species scavengers are responsible for aloe’s antioxidant effects.2
A 1998 study of 35 patients with metastatic cancer taking melatonin concomitantly with aloe showed that aloe may slow the growth of tumors.3 Lack of a control, small study population, and addition of melatonin limited the generalizability of the study, thus providing only preliminary evidence for aloe’s efficacy.
A more recent, nonblinded study evaluated 240 patients with a median age of 64 years and a poor performance status (unable to tolerate aggressive chemotherapy). These patients had metastasis primarily to bone, liver, and lungs and received chemotherapy with or without aloe. Chemotherapy consisted of oxaliplatin plus 5-fluorouracil for colorectal cancer, 5-fluorouracil for gastric cancer, gemcitabine for pancreatic cancer, cisplatin plus etoposide or vinorelbine for non–small cell lung cancer, and cisplatin plus etoposide for small cell lung cancer. Participants received a 10-mL dose of aloe three times daily in a mixture of 300 g of fresh aloe leaves, 500 g of honey, and 40 mL of 40% alcohol.4
The percentage of complete responses plus partial responses, called the objective tumor response rate, was 36% for patients treated with chemotherapy plus aloe versus 19% for those treated with chemotherapy alone. Patients with small cell lung cancer who received aloe had an objective tumor response rate of 61% versus 36% of those not treated with aloe. In addition, patients who received aloe had a higher 3-year survival rate compared with those who received chemotherapy alone (19% vs. 5%). Of note, the small and non–small cell lung cancer groups treated with aloe had a significantly higher rate of 3-year survival.4
The incidence of fatigue or asthenia was lower in patients who received aloe than in those receiving chemotherapy alone (26% vs. 46%). Vinorelbine-induced constipation was reduced in patients taking aloe versus those who were not (18% vs. 71%). Neurotoxicity from oxaliplatin was also decreased in the aloe group (29% vs. 43%).4 These results have not been substantiated in other studies.
Although adverse effects were not reported in this study, concern exists that oral aloe may cause diarrhea, electrolyte abnormalities, and hypoglycemia. Interactions may exist with many drugs.
What to tell patients
Several small studies have assessed the use of oral aloe in patients with metastatic cancer. Although data seem promising, the results are preliminary. Oral aloe vera, depending on the specific plant part used, may possess adverse effects and drug interactions. Encourage patients to avoid use of oral aloe without first consulting their oncologist.
- www.cancer.org/ downloads/STT/CAFF2003PWSecured.pdf
- Planta Med. 2012;78:843–52
- Nat Immun. 1998;16:27–33
- In Vivo. 2009;23:171–5