Mass. Gen. Laws ch. 176A, § 8N

Any contract between a subscriber and the corporation under an individual or group hospital service plan that shall be delivered, issued or renewed in the commonwealth, which provides coverage for prescription drugs, shall provide as benefits to all individual subscribers and members and to all groups having a principal place of employment within the commonwealth, coverage for off-label uses of prescription drugs used in the treatment of cancer as defined in, and subject to the restrictions of, sections forty-seven K and forty-seven L of chapter one hundred and seventy-five.