Kidney cancer: what it is and how to identify it

Kidney cancer: what it is and how to identify it

This type of cancer, also known as renal cancer, starts when abnormal kidney cells start to grow at an uncontrolled rate, forming masses called tumors that spread to other nearby tissues.

The kidneys are responsible for filtering the blood and thus, eliminating excess water, salt and other waste products, all of which are converted into urine that is eventually eliminated from the body.

If you or someone in your family has recently been diagnosed with kidney cancer, it is important that you understand what this type of cancer entails. In this article, we explain its symptoms, how to prevent it and what alternative therapies are available to help with its symptoms.


The kidneys are the organs in the body responsible for excreting waste through the urinary tract, in the form of urine. Thanks to this complex structure, the nutrients required by the body are collected and eventually, whatever is not needed for the body’s metabolic processes is discarded.

Anatomically, the kidney is made up of two large structures. One is called the parenchyma (the roof) and the others are the calyces, which form a series of chambers through which the waste is eventually eliminated. Additionally, there are blood vessels that feed into it and nerves that allow its proper functioning.

In the renal cortex, functional units called nephrons can be found which, together with several other components, form a paper-like filter through which waste is separated from usable products for the body, such as water, salts, minerals, micronutrients, sugars, preventing products like proteins from being eliminated from the body.

Kidney tumors

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There are a several different types of renal tumors. The World Health Organization (WHO) classifies them according to their pathological and genetic characteristics and they can be either benign or malignant.

Benign kidney tumors

  • Renal cortical adenoma. Shares characteristics with papillary carcinoma with malignant characteristics, which requires follow-up.
  • Oncocytoma. Occurs more frequently in men than women, without showing symptoms.
  • Angiomyolipomas. Tumors formed by blood vessels (angio), smooth muscle (myo) and adipose tissue (lipoma) that must be tested for sclerosis; the most serious complication related to this type of tumor is retroperitoneal hemorrhage.

Malignant kidney tumors [H3]

  • Renal cell carcinoma or Adenocarcinoma. Usually large, rounded tumors, representing 80 to 85% of all malignant renal tumors in adults. Most common in men between the ages of 60 and 70. They start in the renal cortex but can invade the medulla and calyx systems.
  • Clear cell carcinoma. Originates in the tubular system (excretory tubules). It is named after its pale color when examined under a microscope, it is of solid growth and can be sporadic or associated with genetic diseases.
  • Papillary carcinomas. Small tumors that originate in the cortex, which are round and usually bilateral.
  • Chromophobe cell renal carcinoma. The least common of renal cell adenocarcinomas. Cells are pale, but much larger than those of clear cell renal cell carcinoma.
  • Nephroblastoma, also known as Wilms’ tumor. This is a tumor that starts in the embryonic stage (before the development of the fetus in pregnancy) or at a very early age. It occurs in children from 2 to 5 years, as a large nontender mass felt in the abdomen; patients may experience pain, fever and bloody urine. Genetic tests should be carried out.

There are other subtypes of renal cell carcinoma that are less common, including: collecting duct carcinoma, multilocular cystic renal cell carcinoma, medullary carcinoma, mucinous tubular and spindle cell renal carcinoma and renal cell carcinoma associated with neuroblastoma. There are also unclassified renal cell carcinomas that do not fall into the previous subcategories, or where more than one type of cell is found.


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Most cases of kidney cancers do not present symptoms in the early stages of the disease or in the case of benign neoplasms, making it difficult to diagnose.

Symptoms can include:

  • Bloody urine
  • Pain on one side of the lower back
  • A growth or lump on the side or lower part of the back
  • Tiredness (fatigue)
  • Loss of appetite
  • Unexplained weight loss
  • Fever that is not caused by an infection and does not go away
  • Anemia (low red blood cell count)


Research has yet to determine a definitive cause of kidney cancer. What we do know is that it is caused by mutations in DNA, but the reason for these abnormal changes is up for debate. However, there are several known risk factors that could increase your chance of suffering from kidney cancer:

Risk Factors

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The following risk factors can increase your chances of suffering from renal cell cancer.

  • Smoking
  • Obesity
  • Family history of kidney cancer
  • Old age
  • Exposure to toxic substances in the workplace
  • High blood pressure (hypertension)
  • Use of certain medication (ask your doctor)
  • Advanced kidney disease
  • Patients undergoing chronic dialysis


There is no definitive way to prevent this type of cancer, but it is possible to reduce the risk factors that could contribute to it. To prevent kidney cancer, you should:  

  • Avoid tobacco consumption and keep your distance from smokers to avoid inhaling secondhand smoke.
  • Follow a healthy diet and exercise regularly to maintain a healthy weight.
  • Drink a lot of liquids, this allows for better circulation.
  • Get treated for high blood pressure.
  • Avoid exposure to toxic substances such as cadmium and organic solvents that could increase your risk of developing renal cell cancer.
  • Avoid taking medication without a prescription, as some medicines have to be excreted by the kidneys and can overload it, particularly certain antibiotics and anti inflammatories like ibuprofen.

Diagnosis and tests

This type of cancer is usually detected around the early stages of the disease, when it is still located in the kidney. As the kidneys are located deep in the body, often the tumors cannot be felt from the surface.

The tests to confirm a kidney cancer diagnosis include:

  • Enquiry into patient’s medical history and a full medical exam: The doctor will ask about symptoms, possible risk factors and the patient’s own medical history, as well as their family´s.
  • Urine test: carried out to detect small quantities of blood or other substances that cannot be seen by looking at the urine. It is estimated that around 50% of patients with renal cell cancer have blood in their urine, although this can also be a symptom of other pathologies, like basic infections.
  • Complete blood test or hemogram: this test measures the existing amounts of the different cells in the blood. Patients with kidney cancer often have a low red blood cell count, specifically a decreased level of hemoglobin (anemia), or an increase in hematocrit levels (polycythemia). These blood counts are essential to determine the overall health of the person and to establish the appropriate treatment.
  • Blood chemistry test: in this type of laboratory test, the doctor will try to determine whether there are any anomalies in the metabolism which could suggest metastasis, so they may ask for calcium, parathyroid hormone, liver and kidney function tests, as well as hormone tests.
  • Computerized Tomography (CT or CAT scan): X rays are taken from different angles to create a three-dimensional image of the inside of the body. Allows for a detailed view of the kidney to determine whether there are any anomalies or tumors.
  • Magnetic Resonance imaging (MRI): instead of X rays, magnetic fields are used to produce detailed images of the inside of the body. Unlike tomography, this exam shows a more detailed view of soft structures, such as organs, tendons, muscles and allows small lesions to be identified, differentiating between cystic and solid lesions and detecting hemorrhages within cysts. Before the test, a special dye is applied to obtain a clearer image of the inside of the body.
  • Ultrasound: sound waves are emitted and allow an image of the inside of the body to be created, revealing whether there are any anomalies present in the structures of the kidney.
  • Positron emission tomography (PET scan): consists of injecting a radioactive sugar substance that is absorbed by cells that are using a high amount of energy (cancerous cells). This study is also called a PET/CT scan because it is combined with a computerized tomography scan, which generates images and allows for the identification of places where this activity is taking place.
  • Intravenous pyelogram: consists of an x-ray of the urinary system that is taken after injecting a special dye. It is useful for finding anomalies in the renal pelvis and urethra.
  • Angiography: a contrast substance (different from the intravenous pyelogram) is used, which allows for a map of the blood vessels to be created that helps to identify and diagnose any alterations in the renal vessels or the possible formation of new vessels that may be feeding a tumor.
  • Chest x-ray: the chest is examined to determine whether the cancer has spread to the lungs.
  • Bone scintigraphy: this test aims to determine whether the cancer has spread to the bones. The PET scan can also reveal this, hence why the scintigraphy is not as common.
  • Kidney biopsy: in this test, a small tissue sample, which consists of cells from the suspected area, is taken and subsequently examined under a microscope.

Classification of the stage of kidney cancer

Once the doctor has confirmed a kidney cancer diagnosis, the next step is to determine exactly what stage the cancer is in order to start suitable treatment.

Every type of cancer can be classified into various stages, depending on where it is located, whether it has invaded nearby structures or if it has metastasized to other distant organs.

The most common staging system for stomach cancer is the TNM system, which defines:

T: size of the tumor

N: the number of nearby lymph nodes that have cancer

M: whether it has metastasized to other areas of the body

Each one of these is evaluated on a scale of 0 to IV according to the degree of severity.

The TNM stage is fundamental for deciding the most suitable treatment according to each individual case.


The patient that has been diagnosed with kidney cancer has various treatment options. Generally, their effectiveness largely depends on the stage of the cancer.

It is important to examine each one of the patient’s alternatives, weighing up the benefits against the possible risks and side effects of each one of the treatment options.

  • Surgery: depending on the type, stage and location of the cancer, as well as other affected tissues, different operations can be carried out to remove the cancer and, sometimes, other tissues near the kidneys. This can be radical i.e. removing the entire affected kidney, or conservative (partial nephrectomy and enucleation or lumpectomy), which is performed when there is a mutation in one kidney or when only one of the two kidneys is working properly.
  • Ablation: in patients in very advanced stages of kidney cancer who are too weak to undergo surgery, other methods are used to destroy tumors (cryotherapy, radiofrequency and arterial embolization).
  • Radiotherapy: uses X-rays, gamma rays, or high energy particles to destroy cancer cells.
  • Chemotherapy: anti-cancer medication is injected into a vein or administered orally. These drugs enter the bloodstream and are distributed all around the body, which makes this particular therapy very useful for treating cancers that have spread.
  • Targeted therapy: certain medicines aimed directly at the genes, specific cancer proteins, or the conditions of the tissue that are contributing to the growth and survival of the cancer cells. This type of therapy focuses on the specific cancer cells, without damaging the normal cells. It can be a useful therapy for treating people that cannot tolerate the side effects of chemotherapy. There are two types: Monoclonal antibodies or small molecule drugs.
  • Immunotherapy: also called biological therapy, it aims to stimulate the body’s immune system (the body’s natural defenses), so that its physiological activities can help fight or destroy cancer cells, preventing mutations in healthy cells.

Complementary treatments

These are carried out in parallel with conventional treatments and, in general, focus on relieving side effects from treatments such as chemotherapy. These treatments can significantly improve patients’ quality of life.

Establishing a suitable support network for the patient and their family should be a top priority, and it should be managed appropriately

The following therapies go alongside traditional treatments:

  • Acupuncture: surgical needles are inserted into strategic points in the body to help the patient overcome the pain and fatigue caused by certain cancer treatments. Can affect the patient’s blood chemistry by increasing the hemoglobin levels and white blood cells responsible for the body’s defenses.
  • Aromatherapy: the use of plant-based essential oils (from flowers, herbs or trees) as a type of therapy to improve physical, emotional and spiritual wellbeing.
  • Meditation: its purpose is to calm the patient’s mind and emotions, so that they reach a state of natural peace and serenity and help them cope with their treatment.
  • Physical therapy: based on moderate, therapeutic exercise and relaxation techniques to improve the patient’s sleep, restore energy levels, prevent a sedentary lifestyle, prevent loss of muscle mass and promote chest expansibility.
  • Psychosocial therapy: consists of the recognition and care of the patient’s emotional state and their surroundings. It is focused on promoting a suitable support network, providing therapy not only for the cancer patient, but also for their family.
  • Homeopathy: studies have found that extracts of Rhus verniciflua Stokes have been shown to eliminate in vitro metastasis. Its main effect is the inhibition of angiogenesis, which means that it prevents the generation of blood vessels that feed the tumor. Some homeopathic medicines, such as Sars, Phyto and Ruta, demonstrated both cytotoxic and antiproliferative activity, whilst others have also been found to play a role in managing the side effects of chemotherapy, such as nausea, loss of appetite, anxiety and depression.
  • Use of cannabinoids: Medicinal cannabis has been proven to be beneficial in treating the side effects caused by cancer treatments. They can reduce nausea and vomiting, stimulate appetite and relieve the pain that some chemotherapy and radiotherapy treatments can produce. The role of cannabinoids in the death of tumor cells by reducing their potential to spread and metastasize, is also being researched. For now, it has been concluded that the cannabinoid receptor 2 may be a determining factor in the progression of renal carcinoma, however, this still requires further research. (*Always check to see if it is legal in your jurisdiction before obtaining any cannabis-based product.)


Galván G, Guajardo R, Quintana O, Rodríguez J. Patología renal. In: Valencia Mayoral P, Ancer Rodríguez J. eds. Patología New York, NY: McGraw-Hill; 2014. Accessed marzo 27, 2019.

Koeppen BM, Stanton BA; Renal Physiology; 5th edition; Philadelphia; Mosby Elsevier; 2013;1-177.