IF you were fired simply for having cancer, that would be illegal: employees may not be fired for having illness or medical conditions.  But if you missed work without having enough paid time off (PTO), such as sick days, to cover the absences, and/or were eligible for (and your company covered by) FMLA and used FMLA leave for the absences, you could be terminated for the absences--the law does not make employers keep employees who miss work without covering their absences by a combination of PTO and/or FMLA leave.If you did not have uncovered absences and believe ou were fired for having cancer, speak to the federal EEOC or your state equal/civil rights agency about filing a complaint.