Hello dear, Thank you for your contact to health care magic. I read and understand your concern. I am Dr Arun Tank answering your concern. Chemotherapy can cause immunosuppression. Immunosuppression is the major cause of the fungal infection in the cancer patient. Fungal infection can cause blackening of the infected part. So if the toe is infected than you should avoid the procedure. Fungus is usually present in all of our surrounding. But we are not infecting with it because we have good immunity. In the same way if you client is neat and clean with good immunity they will not have any fungal infection. It occurs only in immunocomprmise patients. So you can do procedure in them, with good hygieneic condition. With good aseptic procedure it will not spread to others. I will be happy to answer your further concern on bit.ly/DrArun. Thank you, Dr Arun Tank Infectious diseases specialist, HCM.