Is it permissible to give Zakat al-Mal (charity on wealth) to the Cancer Institute or a cancer hospital, knowing that treatment there is free and may benefit the wealthy, and what is the Nisab (minimum amount on which Zakat is due) for Zakat al-Mal and how is it calculated?

A Muslim must allocate Zakat to its legitimate recipients as stated in the Holy Quran. Their obligation is not fulfilled unless the poor person takes possession of it. It is not permissible to give Zakat to charitable organizations if the poor do not take possession of it, or if the organizations do not exclusively ensure benefit for the poor, unless those in charge of these organizations are known for their piety and knowledge and distribute Zakat to its rightful recipients in the form of medicine. Some scholars have permitted this, and the madhhab of Abu Hanifa and Sheikh Al-Islam Ibn Taymiyyah permits giving its monetary value if it is more beneficial for the poor. As for how to calculate Zakat: whoever's wealth reaches the nisab (the equivalent of 85 grams of gold or 595 grams of silver) and a full lunar year has passed, must pay a quarter of a tenth (2.5%) of it as Zakat. Wealth acquired during the year that is an increment to the original capital is zakatable along with it, while wealth that is not an increment to the original capital has its own independent annual cycle.