I've had a light brown spot on my chest for some time ad it's grown to quarter size, but now there's 7 more surrounding it.. could it be cancer?

Don't try to guess: An exam will provide better answers. If the doctor is concerned, a biopsy will yield more info and you'll know. Don't jump to a conclusion and get anxiety over it. Let's hope it's nothing, but find out. Take it to your doctor. Best wishes!

How old are you?: Common skin conditions like fungal infections-Tinea need to be ruled out . Do you having any itching, is the big patch very fastly growing, bleeding on scratching more than usual, then it is to be of concern. Otherwise r/o simple ,common conditions like Tinea(Ring worm), candidiasis(another kind of fungal infection , common in people with sweaty skin, more in diabetics, in obese individuals .