Breast cancer patients using herbal remedies could do more harm than good and delay their recovery, according to a leading breast cancer surgeon.
Treatments including garlic, ginger, turmeric and ginseng have adverse effects on blood clotting, which means that they can prevent healing of skin lesions when breast cancer spreads, explains Professor Maria Joao Cardoso.
Prof. Cardoso, chief breast surgeon at the Champalimaud Cancer Center in Portugal, said there is no evidence that herbal remedies and tropical creams effectively treat skin wounds.
They could end up doing "more harm than good," she told the conference on advanced breast cancer in Lisbon.
She said, "Many patients do not check and tell their doctors that they use complementary treatments.
"Many of these therapies, especially herbal products and topical creams, can have a negative impact on the treatment of cancer.
"Many compounds are complex and some ingredients can delay healing and adversely affect the effectiveness of ongoing systemic treatments."
Breast cancer spreads to the skin in a fifth of cases.
The resulting lesions are difficult to treat and can cause physical discomfort and distress.
Professor Cardoso added: "Laboratory studies have shown that some products can reduce the blood clotting process necessary for healing a wound.
"If a patient has a bleeding wound, these compounds can have a significant negative impact on the healing and effectiveness of the wound dressing."
According to Prof. Cardoso, the prescribed topical treatments can cure or control the wound in only half the cases.
She added that activities such as yoga, acupuncture and Reiki can help patients manage their stress.
Cancer Research UK also claims that complementary therapies can prevent generic treatments from functioning as well as they should.
The charity's website says that it is "concerned" that taking antioxidants, including vitamins A, C and E, can actually protect cancer cells from damage caused by the chemotherapy or radiotherapy.
He adds, "Tell your doctor about any complementary therapies you plan to use, tell them before you start complementary therapy, especially if you are in the process of treating cancer."