Hello, The Yellowish/whitish substance is called smegma. Smegma is a combination of shed skin cells, skin oils, urine, sperm cells and moisture. It occurs in both male and female genital organs. In females, it collects around the clitoris and in males, smegma can collect under the foreskin. There is no evidence that smegma causes penile cancer, but its presence over a long period of time may irritate and inflame the penis, which may increase the risk of cancer. It may also make it harder to see very early cancers. Clean the area beneath your foreskin daily twice after pulling your foreskin back. Hope I have answered your query. Let me know if I can assist you further. Take care Regards, Dr K. V. Anand, Psychologist