Kidney sarcoma is a rare malignant neoplasm that develops from one or more progenitor cell lines of the mesenchymal kidney tissue (muscle, fat, vascular elements). Symptoms in the early stages may be absent, as the tumor grows, there are pulling pains in the lower back on the side of the lesion, macrohematuria, weakness. The diagnosis is based on the results of ultrasound, MRI or CT of the kidneys, histology data, immunohistochemical analysis. Treatment depends on the stage of the oncological process, includes radical or palliative nephrectomy, chemo- and radiation exposure, immunotherapy.
ICD 10
C64 C65
Meaning
Kidney sarcoma can be of different histological types, accounting for about 1% of all renal tumors. Neoplasia is distinguished by the unpredictable nature of the course, the tendency to relapse after surgery. Leiomyosarcoma is the most common histological subtype, accounting for 50-60% of renal sarcomas. Rhabdomyosarcoma, liposarcoma and angiosarcoma are less common. Pathology is diagnosed in adult patients from 28 to 70 years old, men get sick more often, the incidence peaks for each neoplasia differ. The average size of the neoplasm ranges from 5.5 to 23 cm. Children are diagnosed with Wilms sarcoma, light cell sarcoma, rhabdoid tumor.
Causes
The causes of kidney sarcoma, as well as other malignant neoplasms, are still unknown for certain. The neoplastic process is based on a congenital or acquired mutation of genes responsible for the differentiation of renal tissue. Studies have shown a link between kidney cancer and chronic urological pathology: nephrolithiasis, cysts, etc. For an unknown reason, malignant neoplasms in the kidneys are more often found in patients with lymphoma. The main predisposing factors of renal sarcomas:
- Long-term dialysis. Some scientists believe that prolonged replacement therapy increases the risk of kidney tumors. It is possible that the growth of a malignant neoplasm is due to kidney disease, but not from hemodialysis. Research on this issue has not been completed.
- Taking some medications. Receiving immunosuppressive therapy for organ transplantation and systemic diseases changes the reactivity of the immune system. As a result, control over mutated cells is lost, which leads to their active division with the formation of a tumor mass. It has been proven that taking anabolic steroids and phenacetin-containing analgesics can provoke renal cancer.
- Genetic diseases. There are a number of hereditary pathologies, one of the manifestations of which is the neoplastic process in the kidney. As a rule, the tumor is combined with multiple malformations, for example, with Burt-Hogg-Dube syndrome. Burdened family history is also considered as a possible cause of malignant neoplasm of the kidney.
- Lifestyle features. During smoking, along with inhaled smoke, many carcinogenic substances enter the body: benzene, cadmium, arsenic. The so-called co-carcinogens contribute to the realization of their action. There is evidence that obesity increases the risk of developing renal sarcoma. This is probably due to an increase in estrogen levels and the biological activation of insulin-like growth factors.
- High blood pressure. It has been noticed that people suffering from a persistent increase in blood pressure are more often diagnosed with oncological pathology in the kidneys. It is not yet clear what exactly causes the neoplasm – hypertension with its effect on blood vessels, or taking antihypertensive medications, including diuretics.
- Exogenous effects. Contact with asbestos, cadmium and benzene is potentially dangerous for the body. Exposure to radiation, excessive insolation, work related to herbicides have an increased carcinogenic potential. Cases of the disease due to injury to the lumbar region, after transplantation of a donor kidney from a patient with undiagnosed cancer, are described.
Pathogenesis
Carcinogenesis is a multi–stage process, as a result of which normal cells undergo tumor reorganization. Today, the mutation theory is generally accepted. Its main position is that a malignant neoplasm is, in fact, a genetic disease, the cause of which lies in the damage of hereditary material due to mutation. A defect in specific DNA loci leads to uncontrolled proliferation and differentiation of cells. The process is influenced by carcinogenic substances acting as triggers or catalysts.
Classification
In clinical oncourology, primary (from the kidney’s own structures) and secondary (resulting from metastasis from other organs) kidney sarcoma are isolated. By determining the degree of malignancy of the tumor, its progression can be predicted. These data are obtained by morphological examination. There are three degrees of malignancy, they are indicated by the Latin letter G:
- The first one (G1). The histological picture is as close as possible to normal renal tissue. The most favorable type of tumor with low aggressiveness. Slow growth, non-aggressive reproduction is typical.
- The second (G2). Cell differentiation is lower, respectively, the malignant potential is higher, including the ability to metastasize beyond the kidney to neighboring organs and tissues.
- The third (G3). The malignant potential is the highest. There is practically no differentiation of cells. Aggressive growth and active metastasis are expected.
Like all tumors, sarcoma can be classified according to the international TNM system, where T is the size of the tumor, N is signs of metastasis to regional lymph nodes, M is distant metastasis. Kidney sarcoma initially most often (in 90%) spreads to the regional lymphoid tissue, lungs and bones of the skeleton, only in the terminal stage affects the liver. Sometimes brain metastases are registered.
Symptoms
The tumor begins to manifest itself only when it reaches a large size, when it has a compression effect on nerves and blood vessels. During this period, blood pressure may increase with low effectiveness of antihypertensive therapy. As neoplasia progresses, hemorrhages with necrosis of the tumor mass and kidney tissue are possible, resulting in bloody urine. A characteristic feature of renal tumors is total pain–free macrohematuria, in which all portions of urine are uniformly stained with blood.
Pain sensations are more often absent, in a number of observations they are caused by the formation of clots that violate urodynamics. In delicate patients with unexpressed fatty tissue, the tumor can be palpated by palpation in the form of a lumpy, poorly displaced mass with moderate soreness. At stage 3-4, symptoms of cancer intoxication may appear: nausea, lack of appetite, pronounced weakness. At night, many patients sweat profusely, the temperature reaction is normal or slightly elevated.
In the absence of timely treatment or with the progression of kidney sarcoma reaches the terminal stage, which is characterized by a pronounced pain syndrome, implying the constant administration of painkillers and sedatives. Pain in the bones of the skeleton is added, which suggests distant metastasis. Periodic symptoms of renal colic and dysuria can be explained by blockage of blood clots of the ureter and lower urinary tract, which prevents the outflow of urine.
Complications
A complication of renal sarcoma is the addition of chronic kidney disease with an outcome of terminal renal failure. 2% of patients are diagnosed with secondary amyloidosis. The growth of the tumor mass causes compression of the inferior vena cava in 50% of patients, which causes complaints of pain, swelling in the legs, the presence of a venous mesh on the skin in the lower abdomen (6-10%), varicose veins of the spermatic cord (3-5%). In oncourology, varicocele on the right is considered as a symptom suspicious of a kidney tumor.
Metastasis of sarcoma has its own complications. In 25-50% of cases, patients first come to an oncologist with a disseminated form of neoplasia. When the spinal cord is affected, neurological symptoms appear. Foci of sarcoma in the skeleton reduce the density of bone tissue, which leads to pathological fractures. Another well–known complication is Stauffer’s syndrome, which is a response from the liver to renal sarcoma. This paraneoplastic syndrome is manifested by hepatomegaly, increased liver tests and dysproteinemia. When the lungs are involved, shortness of breath is typical, sometimes hemoptysis is observed.
Diagnostics
You can suspect a tumor by the presence of an increased number of red blood cells in the urine. The specialist evaluates complaints, family history (confirmed renal cancer in parents, brothers or sisters). In recent years, the detectability of oncopathology has increased due to the availability of screening ultrasound of the kidneys. In X-ray examinations, renal sarcoma may not differ in any way from other cancers, therefore, final verification is possible only after performing nephrobiopsy. The survey algorithm includes:
- Laboratory tests. In addition to micro- or macrohematuria, protein may be present in the urine. There are no changes in the blood test at the T1-T2 stage, with the progression of the neoplastic process, ESR increases, hemoglobin levels decrease, polycythemia joins. These changes are not pathognomonic, they can be detected in a number of other pathologies of the genitourinary organs. Sometimes a cytological examination of urine is performed.
- Instrumental diagnostics. Ultrasound of the kidneys locates the tumor, its contours and dimensions, but according to the scan data, it is not always possible to determine the relationship of neoplasia with surrounding tissues. For these purposes, MSCT or MRI are more informative, which are prescribed for preoperative planning, clarifying the stage of the tumor process. To diagnose distant metastases, ultrasound of the abdominal organs, CT of the lungs, bone scintigraphy are used. PET shows the most effective dissemination of sarcoma.
Differential diagnosis is carried out with complicated kidney cyst, carbuncle, benign tumors. Renal sarcomas are distinguished by histological types, which is important for choosing management tactics and determining the prognosis. Oncourologists rely on three aspects to confirm renal primary sarcoma: the absence of a history of sarcoma of another localization; the occurrence of a tumor in the kidney, not retroperitoneal; the exclusion of a sarcomatoid variant of renal cell carcinoma.
Treatment
Therapeutic measures depend on a number of factors: the stage of the tumor process, histological analysis, the age of the patient. Before making a decision on management tactics, oncourologists take into account life expectancy (in old age, an active surgical approach is rarely advisable), concomitant pathology. A burdened background (a single kidney, chronic renal failure, other diseases in the decompensation stage) become a serious obstacle to surgery, in such cases it is possible to take cytostatics, radiation exposure, immunotherapy.
Surgical treatment
According to American clinical guidelines, surgery is considered the preferred method of treating kidney sarcoma. Surgical intervention can be performed in an open or endoscopic way. Given the likelihood of metastasis and the associated need to increase the volume of surgery, in some cases open access to the kidney under general anesthesia is preferable. Basic techniques for renal sarcoma:
- Partial nephrectomy. Partial resection of the kidney is allowed at the initial stage. The tumor and part of the healthy tissues surrounding it are excised. In large medical centers, intraoperative biopsy and histological examinations are performed, according to the results, regional lymph nodes can be removed if there are indications. Given the high malignant potential of sarcoma, patients are carefully monitored – every 3 months they do CT of the lungs, MRI of the kidneys, ultrasound of the OBP, etc.
- Radical nephrectomy. At the second stage, radical nephroureterectomy is performed with mandatory dissection of lymph nodes, adipose tissue, and the adrenal gland. When organs are involved, they are partially resected, the tumor thrombus is removed from the NSAID. A relapse of sarcoma may appear in a few years, at the third and fourth stages – in a few months. Therefore, every 12 weeks, patients undergo a dynamic examination.
- Palliative interventions. The kidney is removed at an advanced stage to improve the quality of life of the patient. Organ-bearing surgery relieves the patient from episodes of renal colic, macrohematuria, anemia. Sarcoma can germinate the ureter, which disrupts the outflow of urine. If the severity of the condition does not allow for a nephrectomy, a stent drainage is inserted into the pelvis through the ureter during cystoscopy. Percutaneous puncture nephrostomy can also be performed.
Conservative therapy
Cytostatic drugs and radiation therapy are now used less frequently, as it has been proven that sarcomas do not have a pronounced sensitivity to these methods, and this type of treatment is difficult for patients to tolerate. Non-randomized studies have shown that intraoperative radiation reduces the frequency of local recurrence after radical surgery with a localized tumor by half. Adjuvant administration of cytostatics increases the number of cases of relapse-free survival by 10%.
In metastasis of sarcoma and its relapses, the role of chemo- and radiation therapy is not thoroughly defined. Surgical removal of the lesion remains the method of choice when single metastases or local relapses appear. Some oncourologists perform palliative chemotherapy, which cannot radically cure the patient, but slows down the progression of sarcoma. A number of cytostatics are used in the polychemotherapy mode, which allows to receive a response to treatment in a larger number of patients, but does not affect life expectancy.
Experimental therapy
Relatively recently, targeted therapy has been started, which involves the use of biological features of the tumor to destroy it. Unlike traditional chemotherapy, the method is specific and does not harm normal cells. Molecular-guided therapy refers to a treatment designed to interfere with the function of a biological pathway in a cancer cell that is critical to its growth or survival.
Examples of these pathways include signal transmission, for example, through activation of kinases (enzymes that add phosphates to target proteins, altering their function), programmed cell death (apoptosis), regulation of gene transcription or tumor angiogenesis (growth of new blood vessels). Molecular-oriented drugs are among the most commonly used targeted methods of sarcoma treatment.
The effectiveness of immune therapy is significantly higher than with cytostatics. The use of immune checkpoint inhibitors demonstrated better response results compared to cytokines (interleukin II, interferon) used previously. Modern methods of treatment are gradually replacing the old methods, have fewer side effects. Several drugs are registered annually in the world that give hope for recovery or stable remission to patients with kidney sarcoma, even at advanced stages.
Prognosis and prevention
Numerous clinical trials of new drugs show that the prognosis for renal sarcomas has improved in recent years. Survival correlates with the stage at which the diagnosis was made, the smaller it is, the more chances of a favorable outcome. Thus, at the first stage, 80% of patients experience the ten-year milestone, and at the fourth stage, life expectancy is less than 12 months. Prevention includes adherence to a healthy lifestyle, exclusion of contact with carcinogens, control over body weight.