Toon Arts announced Tuesday that it tested positive for a banned substance in an out-of-competition doping control it underwent 10 days before the UCI Cyclocross World Championships. However, the UCI did not impose a provisional suspension because the substance is a metabolite of the breast cancer drug Letrozole, which is banned for use in and out of competition but is in a class called "specified substances."

Arts voluntarily ended his season and was suspended by his team, Baloise Trek, pending analysis of the B sample.

Letrozole is typically used to treat women with estrogen-dependent breast cancer. Letrozole is an aromatase inhibitor and acts by inhibiting estrogen production in the body. There is no medical use for letrozole in men, and it is banned because it may be used to mask the effects of anabolic steroids or to promote higher testosterone levels by inhibiting hormone breakdown.

The drug is listed in WADA's banned substances as half of the "specific substances" "hormones and metabolic regulators," i.e., hormones produced naturally by the body and common food contaminants, which may be allowed WADA and UCI anti-doping rules allow for reduced suspensions for specific substances, as opposed to anabolic steroids and EPO, which are banned at all times and require a minimum four-year suspension for a positive result.

A positive test for the specified substance letrozole usually carries a two-year suspension, which may be reduced if the athlete can prove that the substance entered his or her system unintentionally, i.e., with no intention to cheat.

Furthermore, the ban can be reduced from one year in either case by proving "no gross negligence or fault" through contaminated supplements, etc.

Fellow cyclocross racer Denise Bessema, who would have been suspended for four years for testing positive for anabolic steroids, was spared a six-month off-season suspension in this manner.

Italian tennis star Sara Errani tested positive for the same drug in 2017. She claimed that her mother had laced her family's tortellini with a breast cancer drug and was initially suspended for two months. However, the Italian anti-doping agency appealed to the Court of Arbitration for Sport, which extended her ban to 10 months.

Coincidentally, Elani was accused in 2012 of having a relationship with Luis Garcia del Moral, a former team doctor for US Postal Service who was permanently banned in the Lance Armstrong case.