Another cancer that occurs in silence

Kidney cancer, it seems that we don't hear this term very often in our daily life, but kidney cancer is one of the three major tumors of the urinary system, second only to bladder cancer in incidence. Although the incidence of kidney cancer is lower than that of bladder cancer, the mortality rate is higher than that of bladder cancer. We must take this terrible cancer seriously.

Kidney cancer is a type of cancer caused by the canceration of kidney cells. Almost all kidney cancers start in the inner layer of the renal tubules. Let's first understand the internal structure of the kidney and find out where the cells start to become cancerous. As part of the urinary system, the kidney filters impurities from the blood and maintains the balance of body fluids and electrolytes in the human body. The figure below is a schematic diagram of the anatomy of the kidney. The numbers in the figure correspond to: 1: renal pyramid, 2: interlobar artery, 3: renal artery, 4: renal vein, 5: renal hilum, 6: renal pelvis, 7: ureter, 8: renal calyx, 9: renal capsule, 10: renal capsule (lower part), 11: renal capsule (upper part), 12: interlobar vein, 13: nephron, 14: renal sinus, 15: renal calyx, 16: renal papilla, 17: renal column. The renal tubule is a part of the structure in the nephron (13 in the figure), and most kidney cancers start here.

Although kidney cancer is also asymptomatic in the early stages and difficult to detect, fortunately, most kidney cancers can be detected before the cancer cells metastasize to other distant organs, because the kidneys are small in size and if a tumor occurs, it is easy to detect. After early detection, the success rate of treatment is naturally higher.

What causes kidney cancer?

The cause of kidney cancer has not yet been identified, but its risk factors have been found to increase the risk of kidney cancer. The first is smoking. Smokers have a higher risk of kidney cancer than non-smokers. At the same time, gender is also a risk factor. Men are more likely to develop kidney cancer than women. The third is obesity. The hormone levels of obese people may change, thereby increasing the risk of cancer. High blood pressure can also be a risk factor for kidney cancer. Some other risk factors, such as exposure to chemical toxins (asbestos, cadmium, benzene, organic solvents, etc.), will increase the risk of kidney cancer. In addition to these environmental and individual factors, some genetic factors can also become risk factors for kidney cancer, such as a family history of kidney cancer or certain family genetic diseases (Hippel-Lindau syndrome or hereditary papillary renal cell carcinoma).

What are the clinical manifestations of kidney cancer?

Common clinical symptoms of kidney cancer are hematuria, abdominal masses, and pain in the waist and abdomen. Because the kidneys are protected by muscles and surrounding tissues in the human body and are located in the hidden retroperitoneal cavity, early-stage kidney cancer tumors are generally asymptomatic, and when obvious symptoms such as hematuria appear, it is usually in the late stage of the disease. Hematuria is the most common first symptom of kidney cancer, but hematuria does not necessarily mean kidney cancer. Some common urinary system inflammations can also cause hematuria. If you have these symptoms, you must see a doctor as soon as possible to rule out the possibility of cancer.

What are the clinical stages of kidney cancer?

The most widely used staging system for renal cancer is the TNM staging system developed by the American Joint Committee on Cancer Staging (AJCC). The staging diagram is as follows:

Stage I: The tumor is no larger than 7 centimeters. Cancer cells are only found in the kidneys.

Stage II: The tumor is larger than 7 centimeters, but the cancer cells are only found in the kidneys.

Stage III: The tumor is any size. The cancer has spread to at least one nearby lymph node or through nearby blood vessels of the kidney.

Stage IV: The cancer has grown through the fatty tissue layer and the outer fibrous tissue layer that surrounds the kidney, or the cancer has spread to several nearby lymph nodes, the lungs, liver, bones, or other tissues.

How is kidney cancer treated?

The treatment of renal cancer is closely related to the type of renal cancer and the clinical stage of the patient. At present, the main clinical treatments for renal cancer are surgical treatment and targeted therapy. Since renal cancer is not sensitive to radiotherapy and chemotherapy, these two treatment methods are basically not used. Patients with renal cancer in stage I-II generally use surgery. Surgical treatment is to remove part of the patient's kidney or the entire kidney through surgery. The operation to remove the entire kidney is called "nephrectomy". Stage III locally advanced renal cancer is mostly treated with surgery combined with systemic treatment, such as surgery combined with targeted therapy. Stage IV metastatic renal cancer is mostly a combination of multiple treatment methods. Surgery removes the primary renal tumor, and then systemic treatment is used to eliminate cancer cells in the patient's body. One of the uncommon renal cancers that needs to be mentioned is Wilms tumor, which is more common in children under 5 years old. Generally, this tumor may have developed in the fetal period of the child, and the symptoms will not begin to show until the child grows up a few years later. For the treatment of Wilms tumor, chemotherapy, radiotherapy, and surgery may all be used in clinical practice, and the specific treatment plan depends on the stage of the child's cancer.

After a complete nephrectomy, what will be the postoperative effects for patients with only one kidney?

Generally, patients can still live a normal life with only one kidney after nephrectomy, but they need to take better care of the remaining kidney than normal people. After patients have only one kidney left, the risk of chronic kidney disease increases, and weakened renal function may also induce cardiovascular disease. Therefore, patients who have undergone nephrectomy need long-term follow-up and regular check-ups to prevent cancer recurrence and surgery-related complications. At the same time, patients need to adjust their lifestyle and eating habits, reduce the intake of red meat and fat, and limit alcohol intake. Common follow-up examinations include abdominal and chest CT scans, ultrasound, urine and blood tests, etc. If the patient relapses during the follow-up period, additional surgery may be required to eliminate the tumor.

How to prevent kidney cancer?

Since the early symptoms of kidney cancer are not obvious, how to prevent kidney cancer has also become a topic of concern to the public. First of all, regular physical examinations are very important for preventing kidney cancer. Ultrasound is the main method for screening kidney cancer, and B-ultrasound is one of the most suitable methods for screening kidney cancer. People with unhealthy lifestyles or family histories of kidney cancer need to undergo regular kidney B-ultrasound examinations, which are very effective for early detection of kidney cancer. At the same time, some risk factors for kidney cancer should be avoided, such as smoking, obesity, high blood pressure and drinking. Here we need to pay attention to some drugs that are prone to cause kidney cancer, such as ibuprofen, naproxen, etc., to avoid overdose, and patients must follow the doctor's advice to take such drugs according to the course of treatment. In short, regular physical examinations and maintaining a healthy lifestyle play an important role in preventing kidney cancer.

References:

[1] Na Yanqun. Chinese Guidelines for Diagnosis and Treatment of Urological Diseases: 2014 Edition [M]. Beijing: People's Medical Publishing House, 2014.

[2] Fan Shengyu. Advances in the diagnosis and surgical treatment of renal cancer[J]. Chinese Journal of Minkang Medicine, 2013, 25(10): 108-109.

[3] Pan Xuewei. Ultrasound diagnosis of small renal cell carcinoma[J]. Chinese Journal of Integrated Traditional Chinese and Western Medicine Surgery, 209, 15(02): 207-209.

[3] Merck Manual of Diagnosis and Treatment. Kidney Cancer [EB/OL]. [2019-08]. https://www.msdmanuals.com/en/home/kidney-and-urinary-tract-disorders/cancers-of-the-kidney-and-genitourinary-tract/kidney-cancer.

[5] Health Pass. Professor Zhang Xuepei: How to prevent kidney cancer that occurs quietly in "silence"? [EB/OL]. [2020-06-13]. https://weibo.com/ttarticle/p/show?id=2309404515317714911312.