Thursday, 4 October 2012

Liver Cancer, Signs of Liver Cancer, Diagnosis of Liver cancer, Treatment of Liver cancer


Hepatocellular carcinoma (HCC, also called malignant hepatoma) is the most common type of liver cancer. Most cases of HCC are secondary to either a viral hepatitis infection (hepatitis B or C) or cirrhosis (alcoholism being the most common cause of hepatic cirrhosis).[1]
Compared to other cancers, HCC is quite a rare tumor in the United States. In countries where hepatitis is not endemic, mostmalignant cancers in the liver are not primary HCC but metastasis (spread) of cancer from elsewhere in the body, e.g., the colon. Treatment options of HCC and prognosis are dependent on many factors but especially on tumor size and staging. Tumor grade is also important. High-grade tumors will have a poor prognosis, while low-grade tumors may go unnoticed for many years, as is the case in many other organs, such as the breast, where a ductal carcinoma in situ (or a lobular carcinoma in situ) may be present without any clinical signs and without correlate on routine imaging tests, although in some occasions it may be detected on more specialized imaging studies like MR mammography.

Signs and symptoms

HCC may present with jaundice, bloating from ascites, easy bruising from blood clotting abnormalities or as loss of appetite, unintentional weight loss, abdominal pain,especially in the upper -right part, nauseaemesis, or fatigue

Risk factors

The main risk factors for hepatocellular carcinoma are:
The risk factors which are most important varies widely from country to country. In countries where Hepatitis B is endemic, such as China, Hepatitis B will be the predominant cause of Hepatocellular Carcinoma.[8] Whereas in countries, such as the United States, where Hepatitis B is rare because of high vaccination rates, the major cause of HCC is Cirrhosis (often due to alcohol abuse).
The risk of hepatocellular carcinoma in type 2 diabetics is greater (from 2.5[7] to 7.1[9] times the non diabetic risk) depending on the duration of diabetes and treatment protocol. A suspected contributor to this increased risk is circulating insulin concentration such that diabetics with poor insulin control or on treatments that elevate their insulin output (both states that contribute to a higher circulating insulin concentration) show far greater risk of hepatocellular carcinoma than diabetics on treatments that reduce circulating insulin concentration.[7][9][10] On this note, some diabetics who engage in tight insulin control (by keeping it from being elevated) show risk levels low enough to be indistinguishable from the general population.[9][10] This phenomenon is thus not isolated to diabetes mellitus type 2 since poor insulin regulation is also found in other conditions such as metabolic syndrome (specifically, when evidence of non alcoholic fatty liver disease or NAFLD is present) and again there is evidence of greater risk here too.[11][12] While there are claims that anabolic steroid abusers are at greater risk[13] (theorized to be due to insulin and IGF exacerbation[14][15]), the only evidence that has been confirmed is that anabolic steroid users are more likely to have hepatocellular adenomas (a benign form of HCC) transform into the more dangerous hepatocellular carcinoma.[16][17]
When hepatocellular adenomas grow to a size of more than 6–8 cm, they are considered cancerous and thus become a risk of hepatocellular carcinoma. Although hepatocellular carcinoma most commonly affects adults, children who are affected with biliary atresia, infantilecholestasisglycogen-storage diseases, and other cirrhotic diseases of the liver are predisposed to developing hepatocellular carcinoma.
Children and adolescents are unlikely to have chronic liver disease, however, if they suffer from congenital liver disorders, this fact increases the chance of developing hepatocellular carcinoma.

Hepatocellular carcinoma, like any other cancer, develops when there is a mutation to the cellular machinery that causes the cell to replicate at a higher rate and/or results in the cell avoiding apoptosis. In particular, chronic infections of hepatitis B and/or C can aid the development of hepatocellular carcinoma by repeatedly causing the body's own immune system to attack the liver cells, some of which are infected by the virus, others merely bystanders.[19] While this constant cycle of damage followed by repair can lead to mistakes during repair which in turn lead to carcinogenesis, this hypothesis is more applicable, at present, to hepatitis C. Chronic hepatitis C causes HCC through the stage of cirrhosis. In chronic hepatitis B, however, the integration of the viral genome into infected cells can directly induce a non-cirrhotic liver to develop HCC. Alternatively, repeated consumption of large amounts of ethanol can have a similar effect. Besides, cirrhosis is commonly caused by alcoholism, chronic hepatitis B and chronic hepatitis C. The toxin aflatoxin from certain Aspergillus species of fungus is a carcinogen and aids carcinogenesis of hepatocellular cancer by building up in the liver. The combined high prevalence of rates of aflatoxin and hepatitis B in settings like China and West Africa has led to relatively high rates of heptatocellular carcinoma in these regions. Other viral hepatitides such as hepatitis A have no potential to become a chronic infection and thus are not related to hepatocellular carcinoma.

[edit]Diagnosis

Hepatocellular carcinoma (HCC) most commonly appears in a patient with chronic viral hepatitis (hepatitis B or hepatitis C, 20%) or/and with cirrhosis (about 80%). These patients commonly undergo surveillance with ultrasound due to the cost-effectiveness.
In patients with a higher suspicion of HCC (such as rising alpha-fetoprotein and des-gamma carboxyprothrombin levels), the best method of diagnosis involves a CT scan of the abdomen using intravenous contrast agent and three-phase scanning (before contrast administration, immediately after contrast administration, and again after a delay) to increase the ability of the radiologist to detect small or subtle tumors. It is important to optimize the parameters of the CT examination, because the underlying liver disease that most HCC patients have can make the findings more difficult to appreciate.
On CT, HCC can have three distinct patterns of growth:
  • A single large tumor
  • Multiple tumors
  • Poorly defined tumor with an infiltrative growth pattern
A biopsy is not needed to confirm the diagnosis of HCC if certain imaging criteria are met.
The key characteristics on CT are hypervascularity in the arterial phase scans, washout or de-enhancement in the portal and delayed phase studies, a pseudocapsule and a mosaic pattern. Both calcifications and intralesional fat may be appreciated.
CT scans use contrast agents, which are typically iodine or barium based. Some patients are allergic to one or both of these contrast agents, most often iodine. Usually the allergic reaction is manageable and not life threatening.
An alternative to a CT imaging study would be the MRI. MRI's are more expensive and not as available because fewer facilities have MRI machines. More important MRI are just beginning to be used in tumor detection and fewer radiologists are skilled at finding tumors with MRI studies when it is used as a screening device.[citation needed] Mostly the radiologists are using MRIs to do a secondary study to look at an area where a tumor has already been detected.[citation needed] MRI's also use contrast agents. One of the best for showing details of liver tumors is very new: iron oxide nano-particles appears to give better results.[citation needed] The latter are absorbed by normal liver tissue, but not tumors or scar tissue.[citation needed]
In a review article of the screeningdiagnosis and treatment of hepatocellular carcinoma, 4 articles were selected for comparing the accuracy of CT and MRI in diagnosing thismalignancy.[20] Radiographic diagnosis was verified against post-transplantation biopsy as the gold standard. With the exception of one instance of specificity, it was discovered that MRI was more sensitive and specific than CT in all four studies.

[edit]Pathology


Micrograph of hepatocellular carcinomaLiver biopsyTrichrome stain.
Macroscopically, liver cancer appears as a nodular or infiltrative tumor. The nodular type may be solitary (large mass) or multiple (when developed as a complication of cirrhosis). Tumor nodules are round to oval, grey or green (if the tumor produces bile), well circumscribed but not encapsulated. The diffuse type is poorly circumscribed and infiltrates the portal veins, or the hepatic veins (rarely).
Microscopically, there are four architectural and cytological types (patterns) of hepatocellular carcinoma: fibrolamellarpseudoglandular(adenoid), pleomorphic (giant cell) and clear cell. In well differentiated forms, tumor cells resemble hepatocytes, form trabeculae, cords and nests, and may contain bile pigment in cytoplasm. In poorly differentiated forms, malignant epithelial cells are discohesive,pleomorphicanaplastic, giant. The tumor has a scant stroma and central necrosis because of the poor vascularization.[21]

[edit]Staging

Important features that guide treatment include: -
  • size
  • spread (stage)
  • involvement of liver vessels
  • presence of a tumor capsule
  • presence of extrahepatic metastases
  • presence of daughter nodules
  • vascularity of the tumor
MRI is the best imaging method to detect the presence of a tumor capsule.

[edit]Prevention

Since hepatitis B or C is one of the main causes of hepatocellular carcinoma, prevention of this infection is key to then prevent hepatocellular carcinoma. Thus, childhoodvaccination against hepatitis B may reduce the risk of liver cancer in the future.[22]
In the case of patients with cirrhosis, alcohol consumption is to be avoided. Also, screening for hemochromatosis may be beneficial for some patients.[



No comments:

Post a Comment