Kidneys do a better job of balancing out fluids.
Even if you could raise urine ph, if you have cancer that means very little.
The ph inside the cancer cell is most crucial to killing the cancer cells.
Typical buffers have been proven not to enter cancer cells so that externally the ph may raise but internally, the cells remain acidic and this keeps oxygen from perfusing into cancer cells.
Strong electron attractors are needed and calcium, sodium, magnesium are weak attractors by virtue of their molecular weight. They do not usually enter cancer cells until the ph of cance cells are so low that the finally enter.
Strong electron attractors are iron, silver, rhubidium, cesium, potassium, selenium, zinc, and sulphur.
Taking baking soda or calcium carbonate is not bad, interstitial fluids, if alkaline will neutralize cancer acid, (uric, lactic, carbonic,) and prevent pain and spreading but just remember it will do little to enter the cancer cell.
So, increasing urinary ph will not mean a whole lot in the long run if the ph inside cancer cells remains acidic.