Carcinomas In The Kidney

Introduction

Before discussing carcinomas, let us see what cancer is. Cancer is an abnormal growth or division of living cells in the body. Cancers can be classified on various bases. Cancer classification based on where the cancer starts

• Carcinomas refer to cancer starting in the epithelial tissues.
• Myelomas refer to cancer starting in the plasma cells.
• Leukaemias refer to cancer starting in the bone marrow.
• Lymphoma refers to cancer starting in the lymphatic system.
• Sarcoma refers to cancer in connective tissues and supportive tissues.
• Mixed cancer refers to cancer that starts in more than one tissue. 

Carcinoma cancers start in the epithelial tissues. Epithelial tissues form the covering of the body surfaces, line body cavities and hollow organs, and are the major tissue in glands. Most of the cancers affecting the skin, neck, pancreas, kidney, liver, breasts, etc, are carcinomas in nature. In carcinomas, tumours are formed in one part of the body, which then spreads to other parts of the body. It implies that carcinomas can metastasize and can affect other body cells.

The kidney is an organ of the body that maintains a balance between water and electrolytes and is involved in the elimination of metabolic wastes from the body. The kidney has millions of functional units known as nephrons. Nephrons are responsible for the removal of waste and excess substances from the blood. The kidney is considered a vital organ of our body, and it is necessary for adequate functioning of the body.¹

Renal impairment can lead to decreased to no elimination of drugs and other metabolic wastes from the body. Accumulation of substances such as drugs due to renal impairment can cause toxicity in the body. In the UK, around 13,300 people get diagnosed with kidney cancer, making it the 7th most common cancer in the UK. 

Types of kidney cancer

There are various types of kidney cancer, a few of them are:

• Renal cell carcinoma (RCC): The tumours in the lining of the kidney tubules are known as renal cell carcinoma. It often stays in the kidneys but sometimes can spread to other parts of the body.  
• Transitional cell carcinoma (TCC): If the malignant cells are present in the renal pelvis and ureter, then it is transitional cell carcinoma 
• Wilms tumour: If the cancer cells develop in children, then it is a Wilms tumour. Wilms tumour is a rare kidney cancer disease affecting children.
• Other rare types: Other rare types of renal cancers are carcinoma in the collecting tubules (when cancer cells develop in the collecting tubules) and renal medullary carcinoma (when the cancer cells develop at the medulla region of the kidneys). Sarcomatoid is another rare type. In this, the cancer cells look like sarcoma cells under the microscope. 

Causes and risk factors of kidney cancer

There is no certain cause for kidney cancer, but there are some risk factors that can increase a person’s chances of developing kidney cancer. They include 

Age, gender, and genetics

Approximately 400,000 cases of RCC are reported worldwide annually. The risk of developing renal carcinoma increases with age and is most commonly seen in AMABs (assigned male at birth) over 60 years of age. People with a family history of renal carcinoma can also develop renal carcinoma. When discussing genetics, two genes (PRC and TFE 3) may be responsible for the development of renal carcinomas.

Smoking, obesity, and hypertension

Smoking can make an individual more susceptible to renal carcinomas. Obesity is also a determining factor in the case of renal carcinomas. The heavier an individual, the higher the risk of developing renal carcinoma. Meanwhile, hypertension has a direct link with RCC. Antihypertensive drugs, such as diuretics, have great suspicion of causing kidney carcinomas.²  

Occupational exposure to certain chemicals

According to a study, there is an increased risk of renal cell carcinoma in AMABs that is associated with occupational exposure to chemicals such as benzene, coal tar, soot, pitch, herbicides, minerals, etc.³

Signs and symptoms of kidney cancer

Blood in urine (hematuria)

Hematuria is the most common presenting sign in the case of kidney cancer. It occurs in 50-60% of the cases. Gross hematuria (blood in the urine is visible to the naked eye) occurs less commonly compared to microscopic hematuria (blood in the urine is visible only under the microscope) in renal cell carcinoma. Gross hematuria with vermiform clots (worm-like clots) and clot formation in the ureters indicate the presence of upper urinary tract bleeding.        

Flank pain

Flank pain may be described as discomfort, distress, or agony in the part of the body below the rib and above the ileum. About one-third of patients present with abdominal pain or flank pain.

Abdominal mass

The pain occurring in the abdominal region is known as abdominal pain. About one-third of patients face abdominal pain. It occurs due to an increase in the size of the kidney tumours and their exerting pressure on the organs present in the abdominal region. 

Fatigue and weight loss

In renal carcinomas, unexplained weight loss occurs accompanied by fatigue. 

Diagnosis and staging of kidney cancer

Diagnosis of kidney cancer

Imaging tests (CT, MRI, ultrasound)

Renal cancer can be detected by various imaging technologies such as a CT scan, MRI, and ultrasound. 

CT scan or computerised tomography, uses computers and X-rays to produce cross-sectional images of your body. 3-D images of soft tissues and bones are produced by utilising X-rays and a series of computers.  

In MRI or magnetic imaging resonance, images of the inside of the body are produced with the help of a large magnet, radio waves, and a computer. 

In the end, ultrasound waves are used to produce images, and then detection of renal cancer is done. 

Biopsy and histopathological examination

In biopsies, a small part of the tissue from the kidney is removed and observed under the microscope. The pathologist will see the presence of any cancer cells in the tissues. 

Staging of kidney cancer

There are four stages of kidney cancer. The stages are as below:

Stage 1: the tumour is less than 7 centimetres and has not spread to other parts of the body 

Stage 2: the tumour is greater than 7 centimetres and has not spread to other parts of the body 

Stage 3: the tumour is in the kidney, the nearby lymph nodes, or the surrounding tissues of the kidney 

Stage 4: the tumour has spread to the lymph nodes, other organs, or the adrenal gland present above the kidneys

Treatment options for kidney cancer

The following are the treatment strategies for the renal cell carcinoma:    

Surgery                                                             

To treat renal cell carcinoma, a part of the kidney tissue or the entire kidney may be removed through surgery. When some of the tissues are removed within the kidney, it is known as a partial nephrectomy. It is usually done for stage 1 kidney cancer or in cases where it is not possible to remove the entire kidney. When the kidney, lymph nodes, surrounding tissues, and adrenal glands are removed, it is known as radical nephrectomy.

Radiation therapy

As its name indicates, high-energy X-rays or other radiation may be used to treat cancer. They are bombarded on the site from the outside of the body. They have the potential to either kill or inhibit the growth of abnormal cells. Radiation therapy is used as palliative therapy while treating carcinomas in the kidney. 

Chemotherapy and targeted therapy

In chemotherapy, the drugs are administered from the outside, and they either inhibit or kill the cancer cells. Chemotherapy has one disadvantage: it may kill or inhibit other normal cells of the body and alter normal bodily functions. Axitinib, avelumab, etc., are some of the approved drugs that are given during chemotherapy. Monoclonal antibodies or kinase inhibitors may be given to specifically. Target the abnormal cancer cells.  

Immunotherapy

In immunotherapy, a substance is given from outside of the body that either enhances or restores the impaired immune defences of the body. Thus activating the immune system and acting against the cancer cells. The following therapies may be used in immunotherapy to treat renal cell carcinoma: 

• PD-1 and PD-L1 inhibitor therapy 
• Interferon 
• Interleukin-2

Follow-up for kidney cancer

Renal cell carcinoma has a recurrence rate of 20-30%.⁴ This means there are good chances of the patient getting renal cell carcinoma again. So it is essential to have regular monitoring post-treatment. The same tests that were done for the diagnosis of renal cell carcinoma will be done to keep track of the cancer after the treatment has been done. This is called follow-up tests. Whether further treatment is required or whether there is a need to make changes to the treatment is decided based on the follow-up tests. 

Prevention and lifestyle modifications

Though kidney cancer cannot be prevented completely, there are ways to minimise the chances of getting it. Some of them include:

Quit smoking and avoid exposure to chemicals

Avoiding smoking can help prevent renal cell carcinoma. Smoking may trigger several mechanisms in the body that, in the long run, can cause abnormal cell division. As mentioned above, occupational exposure to chemicals such as benzene, pitch, soot, etc can result in the triggering of renal cell carcinoma. Therefore, one must make sure not to get exposed to chemicals occasionally. 

Maintain a healthy weight and blood pressure

Maintaining a healthy weight and blood pressure is also necessary to prevent renal cell carcinoma. Obesity can lead to several comorbidities, resulting in high cholesterol levels and, thus, impaired renal functions. 

Regular exercise and a balanced diet

Regular exercise can prevent a lot of diseases and conditions. Exercise keeps your body at normal working capacity and helps an individual to carry out tasks. In the prevention of every disease, regular exercise is emphasised.  Therefore, regular exercise is recommended and considered an option to prevent renal cell carcinoma. With regular exercise, a balanced diet is recommended. Free of chemicals and toxins that can reduce an individual's chances of getting renal cell carcinoma. 

Early detection and screening

If early detection is done at a stage where the tumour has not spread to the other parts of the body, the survival rate can be increased to 93%. Therefore, early detection of initial symptoms is recommended. 

Summary

Carcinomas are a type of cancer that originates in the epithelial tissues, which line body surfaces, cavities, and organs. Kidney cancer, specifically renal cell carcinoma (RCC), is a common type of carcinoma that affects the renal cells in the kidney tubules. RCC can spread to other parts of the body and significantly impact kidney function. The exact cause of RCC is unknown, but risk factors that increase an individual's chances of getting it are age, gender, genetics, smoking, obesity, hypertension, and occupational exposure to certain chemicals. Symptoms of kidney cancer include blood in the urine, flank pain, abdominal mass, fatigue, and unexplained weight loss. This can be diagnosed with imaging tests such as CT scans, MRI, and ultrasound, as well as biopsy and histopathological examinations. 

The staging of kidney cancer is based on the tumour size and spread. Based on this, treatment options for RCC are decided. Treatment options include surgery (partial or total nephrectomy), radiation therapy, chemotherapy, targeted therapy, and immunotherapy. After treatment, follow-up tests are conducted to monitor the patient's condition and check for any signs of recurrence because kidney cancer has a recurrence rate of 20-30%. You can reduce your risk of developing kidney cancer by making lifestyle modifications such as quitting smoking, avoiding exposure to chemicals, maintaining a healthy weight and blood pressure, engaging in regular exercise, following a balanced diet, and early detection through screening. Please visit your healthcare provider if you notice any of the symptoms mentioned above.