What are Kidney Cancer Subtypes?

Introduction

Kidney cancer is a complex disease that includes a variety of different types, or subtypes, each with its own unique characteristics and behavior. Knowing the specific subtype of kidney cancer is important because it influences treatment decisions, prognosis, and long-term management. Some subtypes are slow-growing and easily treated, while others are aggressive and require more intensive care. Understanding these differences helps patients and families make informed choices and prepares them for the road ahead.

What are Kidney Cancer Subtypes?
Kidney cancer encompasses a diverse group of subtypes, each with distinct characteristics, genetic mutations, and treatment responses. Clear cell renal cell carcinoma is the most common subtype, but other subtypes such as papillary renal cell carcinoma, chromophobe renal cell carcinoma, and transitional cell carcinoma also contribute to the complexity of the disease. Rare subtypes, including Wilms tumor, renal sarcoma, collecting duct carcinoma, and medullary carcinoma, present unique challenges in diagnosis and treatment. Image Credit: Deka Saputra via Canva.com

Understanding Kidney Cancer and Its Subtypes

A kidney cancer subtype refers to the specific type of kidney cancer based on how the cancer cells look under a microscope and how they behave. Kidney cancers are not all the same, and the differences between them affect how doctors approach diagnosis, treatment, and prognosis. Identifying the subtype is crucial because it helps predict how fast the cancer might grow, how likely it is to spread, and what treatments are likely to work best. Knowing the subtype offers patients a clearer picture of what to expect and helps healthcare teams design personalized care plans that offer the best chance of success.

Major Subtypes of Kidney Cancer

Clear cell renal cell carcinoma, often abbreviated as ccRCC, is the most common form of kidney cancer, making up about 70 to 80 percent of all cases. It is called "clear cell" because the cancer cells look clear under a microscope. This subtype tends to grow more quickly than some others, and while many cases are treatable when caught early, it can be aggressive if it spreads.

Papillary renal cell carcinoma, or pRCC, is the second most common subtype of kidney cancer, accounting for about 10 to 15 percent of cases. This form of kidney cancer is characterized by the formation of finger-like projections inside the tumor when viewed under a microscope. Papillary RCC tends to grow more slowly than clear cell RCC in many cases, although some tumors may behave more aggressively depending on their individual features.

Chromophobe renal cell carcinoma is a rare form, making up about 5 percent of kidney cancers. It generally has a better prognosis and grows slower compared to clear cell carcinoma.

Collecting duct carcinoma is very rare and aggressive. It arises from the ducts that collect urine within the kidney and is harder to treat. Renal medullary carcinoma is an extremely rare and highly aggressive cancer almost always found in young individuals with sickle cell trait.

Lastly, unclassified renal cell carcinomas are tumors that do not fit neatly into any of the other categories and often have varied behavior, sometimes behaving aggressively.

Rare and Less Common Kidney Cancer Subtypes

Several rare kidney cancer subtypes are less frequently discussed but important to recognize. Translocation renal cell carcinoma is a rare form more often found in younger patients and involves specific genetic changes in the tumor cells. Mucinous tubular and spindle cell carcinoma is another rare and typically slow-growing subtype that usually has a good outcome if caught early. Tubulocystic renal cell carcinoma, characterized by cyst-like and tubular structures within the tumor, is also rare and often has a more favorable prognosis. 

Renal oncocytoma is a unique case because although it forms a tumor in the kidney, it is considered benign and not truly cancerous. However, it is sometimes difficult to distinguish from malignant tumors without surgery. Other rare renal tumors include multilocular cystic renal cell carcinoma and succinate dehydrogenase-deficient renal cell carcinoma, both of which have distinct features and require specialized care for accurate diagnosis and treatment planning.

How Are Kidney Cancer Subtypes Diagnosed?

Diagnosing the specific subtype of kidney cancer involves several steps and requires specialized tests. Doctors usually start with imaging studies such as a CT scan or MRI to identify a suspicious mass and assess whether it may have spread. However, imaging alone cannot always determine the exact subtype. A biopsy is often performed, where a small sample of the tumor tissue is removed with a needle and examined under a microscope. 

Pathologists look at the shape, size, and characteristics of the cancer cells to classify the subtype. In some cases, additional tests such as immunohistochemistry or genetic studies are used to detect specific markers that help identify rarer forms of kidney cancer. While imaging provides valuable information about the tumor’s size and location, tissue analysis remains the gold standard for determining the exact subtype and guiding treatment decisions.

Treatment Approaches Based on Kidney Cancer Subtypes

The treatment plan for kidney cancer is strongly influenced by the subtype identified. For clear cell renal cell carcinoma, surgery is often the first step if the tumor is localized, followed by targeted therapy or immunotherapy if the disease is more advanced. Papillary renal cell carcinoma may also be treated with surgery, and targeted therapies specific to the molecular changes found in this subtype are being explored. Chromophobe renal cell carcinoma, due to its slower growth, often responds well to surgery alone without the need for additional treatments unless it has spread. 

Collecting duct carcinoma and renal medullary carcinoma, because of their aggressive nature, typically require a combination of surgery, chemotherapy, and sometimes experimental treatments through clinical trials. Understanding the subtype helps doctors predict which treatments are likely to work best and tailor therapy accordingly, offering the patient the best possible outcome.

Prognosis and Survival Based on Subtype

The subtype of kidney cancer plays an important role in determining prognosis and long-term survival. Clear cell renal cell carcinoma has a wide range of outcomes depending on the stage at diagnosis. Early-stage tumors are often curable with surgery, while more advanced cases may require a combination of therapies and careful monitoring. Papillary renal cell carcinoma is now understood as a single, diverse group without a strict division into type 1 and type 2. Instead, the behavior of individual tumors can vary, with some growing slowly and others showing more aggressive features based on their underlying molecular characteristics.

Chromophobe renal cell carcinoma usually carries a favorable prognosis because it grows slowly and is less likely to spread. In contrast, collecting duct carcinoma and renal medullary carcinoma are associated with poorer outcomes due to their aggressive nature and tendency to spread early. Unclassified renal cell carcinomas have unpredictable behavior, and prognosis depends on specific features identified in the tumor. Knowing the subtype helps patients and their care teams better understand what to expect and plan appropriately.

Additional Information About Kidney Cancer Subtypes

It is possible for a kidney tumor to contain features of more than one subtype, known as a mixed histology. These tumors can be more challenging to treat because they may behave more aggressively than single-type tumors. Rare kidney cancer subtypes, while individually uncommon, collectively make up an important portion of kidney cancer cases and require specialized diagnosis and management. Some patients wonder if a kidney cancer can change subtype over time. While the original subtype generally stays the same, cancer cells can evolve and develop new characteristics, especially under treatment pressure, which may affect how they respond to therapies. These changes are not considered true subtype shifts but are important to consider when planning ongoing treatment.

Conclusion

Kidney cancer is not a single disease but a collection of different subtypes, each with its own characteristics, challenges, and outcomes. Understanding the specific subtype of kidney cancer is critical for selecting the most appropriate treatment, predicting the likely course of the disease, and setting realistic expectations for recovery and long-term health. Advances in diagnostic techniques and targeted therapies have improved the ability to personalize treatment for each patient based on their cancer’s unique features. 

Whether dealing with a common form like clear cell carcinoma or a rare subtype like renal medullary carcinoma, being informed about the differences between kidney cancer subtypes empowers patients and their families to make better decisions and take an active role in their care journey.

Help Others Understand Kidney Cancer Subtypes

If you found this article helpful, please consider sharing it with friends, family, or on social media. You are also welcome to leave a comment or share your story to support others who may be facing a kidney cancer diagnosis.

References

  1. Capitanio U, Montorsi F. Renal cancer. Lancet. 2016 Feb 6;387(10021):894-906. https://doi.org/10.1016/S0140-6736(15)00046-X
  2. Moch H, Cubilla AL, Humphrey PA, Reuter VE, Ulbright TM. The 2016 WHO Classification of Tumours of the Urinary System and Male Genital Organs – Part A: Renal, Penile, and Testicular Tumours. Eur Urol. 2016 Jul;70(1):93-105. https://doi.org/10.1016/j.eururo.2016.02.029
  3. Linehan WM, Ricketts CJ. The Cancer Genome Atlas of renal cell carcinoma: findings and clinical implications. Nat Rev Urol. 2019 Aug;16(8):539-552. https://doi.org/10.1038/s41585-019-0217-0
  4. Choueiri TK, Motzer RJ. Systemic Therapy for Metastatic Renal-Cell Carcinoma. N Engl J Med. 2017 Mar 16;376(4):354-366. https://doi.org/10.1056/NEJMra1601333
  5. World Health Organization (WHO). Kidney cancer. World Health Organization; 2022. Available from: https://www.who.int/news-room/fact-sheets/detail/cancer

Comments

Post a Comment

Popular posts from this blog

What is Blood in the Urine or Hematuria?

Image
Introduction Blood in the urine, medically known as hematuria, is a condition where red blood cells are present in the urine. Hematuria can be alarming, but it is not always a sign of a serious medical condition. It can be caused by a wide variety of factors, ranging from infections to more serious conditions such as kidney disease or bladder cancer. This guide provides an in-depth explanation of what hematuria is, its causes, types, symptoms, diagnostic methods, treatment options, and prevention strategies. By understanding the potential causes and how it is diagnosed and treated, patients and their loved ones can be better informed about this condition. Hematuria, or blood in the urine, can be a symptom of a variety of conditions, ranging from minor infections to more serious issues such as kidney disease or cancer. While it can be alarming, it is important to seek medical evaluation to determine the underlying cause and receive appropriate treatment. Understanding Hematuria Hematur...
Read more

What is Protein in the Urine or Proteinuria?

Introduction Proteinuria, or the presence of protein in the urine, is a condition that can be an indicator of underlying health issues, particularly those related to the kidneys. While it is normal for urine to contain a very small amount of protein, larger amounts may signal that the kidneys are not functioning properly. Proteinuria can be temporary and harmless, or it can be a sign of a more serious condition such as kidney disease or hypertension. This guide aims to provide a comprehensive overview of proteinuria, its causes, symptoms, diagnostic methods, treatment options, and preventive measures. It is designed to help patients, their families, and the general public better understand this condition and its implications for health. What is Proteinuria? Proteinuria is the medical term for the presence of excess protein in the urine. Under normal circumstances, the kidneys filter waste products from the blood while keeping essential substances, such as protein, in the bloodstream. H...
Read more

How do the Kidneys Regulate Blood Pressure?

Introduction Blood pressure is an essential aspect of overall health, influencing many bodily functions, including those of the kidneys. The kidneys, in turn, play a vital role in regulating blood pressure. The relationship between blood pressure and kidney health is a two-way connection—high blood pressure can damage the kidneys, while unhealthy kidneys can cause blood pressure to rise. Understanding how blood pressure affects the kidneys and how maintaining healthy blood pressure can protect kidney function is critical for preventing serious health complications. The Role of the Kidneys in Regulating Blood Pressure The kidneys are responsible for filtering waste and excess fluids from the blood to produce urine. In addition to this vital function, the kidneys help regulate blood pressure by controlling the balance of fluids and electrolytes, such as sodium and potassium, in the bloodstream. The kidneys also produce hormones that influence blood pressure. One of the key hormones produ...
Read more