What is kidney cancer?
O kidney cancer (kidney cancer) is the disease caused by a tumor that grows slowly in the renal parenchyma, that is, in the inner part of the kidney, where the functional units of the organ are located. O kidney cancer has an estimated average growth of 30-35 mm / year. Kidney cancer accounts for 2-3% of all malignancies. It affects twice as many men as women and is more prevalent after 60 years.
There are several histological types and the most frequent is clear cell carcinoma, occurring in 75-85% of cases, followed by:
- papillary carcinoma,
- tumor of the collecting ducts and
They may be associated with several hereditary syndromes.
There are no symptoms in patients with localized kidney cancer, usually being discovered by imaging to investigate abdominal pain. They currently represent 60-70% of diagnosed cases.
O advanced kidney cancer it can be bulky, causing mass effect, compression to neighboring organs or structures, it can be palpated or deform the abdominal silhouette, generating dull or heavy back pain. Invasion of the renal vein and vena cava by tumor thrombus may occur. However, when the tumor invades the excretory route, colic and hematuria may occur, which reflects obstruction of the ureter compromising the drainage of urine into the bladder. In addition, other symptoms such as fatigue, weight loss and appetite, fever without infection and anemia may occur.
The kidney is extremely vascularized and the rupture of the vessels can cause bleeding and is sometimes abundant in the excretory pathway. Therefore, blood in the urine (hematuria) may be a sign of urinary tract disease.
Risk factors of kidney cancer
A systemic arterial hypertension e smoking are risk factors. The relative risk increases progressively with body mass index. There is a strong association between female obesity and CR. Furthermore, other factors that can trigger its onset are due to occupational exposure to cadmium (RR 1,4), hydrocarbon derivatives (gasoline - RR 1,6), asbestos (RR 2,0) and aromatic hydrocarbons (paints) .
Attention should be paid to patients with renal failure who undergo dialysis, develop 40-50% renal cystic lesions (acquired cystic kidney disease) and 6% develop CR. These patients must undergo renal ultrasound annually, after the third year of dialysis. People with hereditary von Hippel-Lindau disease may develop kidney cancer.
In addition, patients with first-degree relatives with kidney cancer or with different tumors of rare origin are also predisposed to the disease. Patients who have had tumors in several organs, tumors associated with other birth defects, tumor in a rare location and who had cancer at a young age are at risk for kidney cancer.
The majority of patients with renal masses are discovered incidentally and associated with increased imaging tests over the past few decades. On the other hand, the incidence of metastatic disease can reach 30% in population studies.
However, the classic triad of kidney cancer diagnosis: flank mass, hematuria and pain currently occurs in 10% of patients.
Solid renal tumors larger than 4 cm should be seen as renal carcinomas. Currently, percutaneous biopsy can be indicated to define the histological diagnosis, however it is indicated in cases where the conduct of partial nephrectomy can be postponed.
In the initial phase, the suspicion of the disease occurs during investigation of a mass or renal cyst detected in an imaging exam. Thus, renal cysts with dense internal content or mass must be seen as cancer, until proven otherwise.
Solid lesions are assessed by tomography or MRI, usually using contrast. In this way it is even possible to suggest your histological diagnosis. On the other hand, solid kidney lesions with fat content, most of the time, because they are caused by a benign disease, the angiomyolipoma.
Treatment of kidney cancer
Patients with kidney tumor up to 4 cm are usually cured by partial nephrectomy (surgical removal of part of the kidney) or ablation by cryotherapy (a technique that uses extremely cold temperatures to destroy the tumor) or radiofrequency. However, some tumors up to 7 cm, exophytic (which grow outside the organ) can still be subjected to partial nephrectomy. However, large tumors are treated by radical nephrectomy, and the kidney is removed within its fatty envelope with regional lymph nodes.
On the other hand, patients with metastatic disease should always be diagnosed by biopsy of the metastasis or the primary tumor. They are treated with target drugs, which can reduce the volume of the primary tumor and / or metastases, so as a result they may or may not have their kidneys removed.
Prevention of kidney cancer
The prevention of kidney cancer can be done by avoiding obesity, high blood pressure, nephrotoxic drugs, exposure to herbicides, cadmium, organic solvents (trichlorethylene).
In patients with hereditary kidney cancer, they usually have autosomal dominant inheritance and should be followed closely with annual imaging exams:
- von Hippel-Lindau syndrome,
- hereditary papillary renal carcinoma,
- leiomyoma and hereditary renal cell carcinoma,
- Birt-Hogg-Dube syndrome)
Thus, these patients should be assessed for the risk of developing kidney cancer in their follow-up. Therefore, attention should be given to patients with risk factors and, therefore, imaging examinations should be performed annually.