Kidney cancer occurs when the cells in the organ mutate and spread uncontrollably. While there are different types of kidney cancer, renal cell carcinoma is one of the most common among adults. Our kidneys remove toxins from the blood and flush out excess fluids. Cancer can affect these functions and lead to several other complications. Here are a few silent yet concerning signs of kidney cancer that one must never ignore. Hematuria The kidneys’ primary function is to remove toxins from the blood. However, cancer can damage the organ’s tissue and affect this function. Consequently, the kidneys can release blood that gets mixed with the urine, causing it to turn dark red, pink, or cola-colored. It is one of the first signs of kidney failure caused by progressive cancer. Pain on one side The kidneys are located in the lower back. When the organ is damaged, it may unexpectedly trigger sharp pain in this region. If one does not have injuries or underlying health complications that could cause this pain, they should get checked for kidney cancer. The pain can develop on either side as two kidneys function simultaneously. Swelling A swelling in the ankles and feet is one of the more visible signs of kidney damage.