Cansema

Black salve, also known by the brand name Cansema, is a dangerous and controversial alternative cancer treatment. The product is commonly classified as an escharotic—that is, a topical paste which burns and destroys skin tissue and leaves behind a thick, black scar called an eschar. Escharotics were widely used to treat skin lesions in the early 1900s, but have since been replaced by safer and more effective treatments. Escharotics, such as black salves, are currently advertised by some alternative medicine marketers as treatments for skin cancer, often with unsubstantiated testimonials and unproven claims of effectiveness.

The U.S. Food and Drug Administration has listed Cansema as a "fake cancer cure" and warns consumers to avoid it.

Cancer salves were first documented as a form of quackery in a 1955 Time article:

Although more recent reports document that some alternative medicine practitioners use the Internet to market escharotics as purported "cures" for skin cancer, they are not recommended as treatments for skin lesions or skin cancer by medical authorities. The effectiveness of escharotics is unproven, while safer and more effective conventional treatments exist for skin cancers, such as: cryotherapy; topical agents such as imiquimod, fluorouracil and Ingenol mebutate; radiation therapy; and surgical excision, including Mohs surgery (microscopically controlled surgery used to remove and test cancerous tissue).

Escharotics can cause serious scarring and damage to normal skin. Their manufacture is largely unregulated, so the strength and purity of marketed products are unknown and unverified. Numerous reports in the medical literature describe serious consequences of using escharotics in place of standard treatments for skin cancer, ranging from disfigurement to preventable cancer recurrences. The website Quackwatch posted a warning against the use of escharotics in 2008. The site collected a variety of sourced documents compiling issues of patient injury from the use of escharotics. A recent study revealed that many individuals who have used black salve were unaware of its potential dangers. In a 2016 news release titled "Beware of black salve," the American Academy of Dermatology urged patients to consult a dermatologist before using home remedies for skin cancers.

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Wikipedia