Eat healthy. exercise. avoid smoking. why did i get maxillary sinus cancer?

Uncertain: Genetic susceptibility and environmental factor usually determine the occurrence of cancers. The extent of the role of one or the other factor are often unclear and intertwined. Exposure to some metals is associated with sinus cancer, however in most case the cause may remain undetermined.

Exposure: Some evidence points to exposure to certain inhaled industrial chemicals, dusts, or metals. Hpv (human papilloma virus) infection is also associated with maxillary sinus cancer. There's good info here: http://www.Cancer.Gov/cancertopics/pdq/treatment/paranasalsinus/patient.