I have a lump on my lower back above the buttocks, is cancer ? its painless, im really worried

It depends on the si: Any lumps that are pailess and growing in size over a period of 1 or 2 months require examination by a physician to check for cancer. I would not be concerned unless it has a size over a quarter(one inch or more)and it has been present more than 4-6 weeks and appears to be getting bigger.

Probably not: It depends on your age and exact other symptoms. Pilonidal cysts are quite common in this location, but they usually have hair or drainage associated with them. Is it a mass? Is it soft and pliable? Could be a lipoma. If it is hard, irregular borders, and immobile, that is more concerning. Probably should get it looked at.