The author is not precluded from doing so through the use of "cost/cure" or "cost/year of life gained". If efficacy and tolerability is demonstrated, however, then a simple comparison of "cost/course of treatment" can suffice for the purpose of comparing two or more therapeutically equivalent treatment alternatives.
The author is not restricted from employing "cost/cure" or "cost/year of life gained". However, if efficacy and tolerability are proven, comparing "cost/treatment duration" would suffice to assess various therapeutic options that are equally effective.