RCW 48.20.397

No person engaged in the business of insurance under this chapter may refuse to issue any contract of insurance or cancel or decline to renew the contract solely because of a mastectomy or lumpectomy performed on the insured or prospective insured more than five years previously. The amount of benefits payable, or any term, rate, condition, or type of coverage shall not be restricted, modified, excluded, increased, or reduced solely on the basis of a mastectomy or lumpectomy performed on the insured or prospective insured more than five years previously.