Drug shortage: why?

98.9% of US oncologists polled for a recent survey say they have experienced shortages of cancer drugs in the last year, and that as a result of the shortages, cancer has progressed in more than 60% of their patients.

Over 70% of patients have experienced more severe side effects as a result of the shortages, add the oncologists, responding to a survey conducted by the Community Oncology Alliance (COA). Almost half of the physicians also reported that they were seeing more than one patient per day affected by a drug shortage, and 58.2% say the shortage of cancer drugs is increasing.

In addition, over 80% of the patients and more than 90% of the practices affected by a cancer drug shortage experienced a more severe financial burden, says the COA.

I do not understand the situation: the logic should be following:

Cancer medicine is expensive and makes huge profit for Big Pharma

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Every medicine vial sold gives a profit to Big Pharma

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There should be no any medicine shortage due to the shortage presupposes shortage of sales and profit.

But the phenomenon of shortage does exist which means that something in our scheme is missing… What is missing? So far I do not know but I am convinced that somebody has to get benefits (political if not direct financial and economic ones) from this situation and I guess it should be Big Pharma. In which way? It will be clear very soon…