Can melanoma cause iron deficiency?

Yes possible: As we depend on the iron in our diet to supply us with our needs, iron deficiency anemia will occur more quickly if a person's intake is poor for any reason or the quality of their diet is unsatisfactory. This could happen when people with melanoma which spread to the whole body.

Short answer no: Most melanomas originate from the skin and do not cause anemia, occasionally with melanoma which has extensively spread to other organs or rarely if melanoma starts in the intestines could it cause iron defiency anemia but this would be very rare.

Yes: Melanoma that has spread to the stomach or GI tract and cause bleeding that can lead to iron deficiency anemia.