An HMO has told the doctor and parents of a four-month old St. Louis boy that it will not pay for his cancer treatments after all. The child was born with a malignant mole on his head, which was removed, but later tests showed the cancer had entered his skull and the lining of his brain. The boy’s doctor tells the St. Louis Post-Dispatch the insurance company, GHP, had given pre-approval for drug therapy for the boy and had started the treatment. But three days later, GHP told him the approval had been cancelled. The insurance company says the drug being used has been approved for adults, but not children. The family has complained to the State Insurance Department.