If you're looking at long-term outcomes in a large cohort, the day-to-day fluctuations may average out, and the logistical benefits of an oral tablet for a year-long study are simply too massive to ignore
Bezin, J., Gouverneur, A., Pnichon, M., Mathieu, C., Garrel, R., Hillaire-Buys, D., Pariente, A., & Faillie, J.-L
Inadequate intake of key vitamins and minerals can impede the hair growth cycle, resulting in slower regrowth during or after a period of hair loss
Those improvements, however, are not believed to last once the drug is discontinued
The boxed warning exists as a precaution based on animal data, not because humans have actually developed these tumors from the medication