She’s not wrong about this.
Medicare pays average sales price plus 6% for chemotherapy drugs. Large oncology practices with buying power negotiate lower than average prices from distributors while smaller practices typically pay more but everyone receives the same reimbursement. So, yes, oncologists do make money on chemotherapy and, frankly, it has been a obstacle (among others) to the uptake of personalized medicine where genomic testing may indicate a more effective treatment.
In fact, in the early 2000s the Medicare reimbursement changed from average wholesale price plus 15% to average sales price plus 6% which significantly narrowed the margin made on drugs. As a result, the total amount of chemotherapy prescribed increased significantly. I wish it wasn’t true but like everywhere cost plus payment tends to yield more cost to generate more payments. In this case, the narrowing of margin produced more cost as physicians seemed to solve back for their otherwise lost income.