Which one of the following may be used to monitor patients with colorectal cancer?
Correct Answer B: Carcinoembryonic antigen may be used to monitor for recurrence in patients post-operatively or to assess response to treatment in patients with metastatic disease.
Colorectal cancer: screening:
Overview:
At colonoscopy, approximately:
A 66-year-old woman with a history of chronic kidney disease stage disease 4 metastatic breast cancer is admitted with a swollen right calf. Investigations confirm a deep vein thrombosis and she is started on treatment dose dalteparin. As she has a significant degree of renal impairment it is decided to monitor her response to dalteparin.
What is the most appropriate blood test to perform?
Correct Answer A: There are two main types of heparin - unfractionated, 'standard' heparin or low molecular weight heparin (LMWH). Heparins generally act by activating antithrombin III. Unfractionated heparin forms a complex which inhibits thrombin, factors Xa, IXa, XIa and XIIa. LMWH however only increases the action of antithrombin III on factor Xa.
The table below shows the differences between standard heparin and LMWH:
Heparin-induced thrombocytopaenia (HIT):
Both unfractionated and low-molecular weight heparin can cause hyperkalaemia. This is thought to be caused by inhibition of aldosterone secretion.
Heparin overdose may be reversed by protamine sulphate, although this only partially reverses the effect of LMWH.
A 52-year-old man with a history of anaemia and abdominal discomfort is diagnosed as having chronic myeloid leukaemia.
What is the mechanism of action of imatinib?
Correct Answer B: Chronic myeloid leukaemia - imatinib = tyrosine kinase inhibitor.
Imatinib is an inhibitor of the tyrosine kinase associated with the BCR-ABL defect.
Chronic myeloid leukaemia:
The Philadelphia chromosome is present in more than 95% of patients with chronic myeloid leukaemia (CML). It is due to a translocation between the long arm of chromosome 9 and 22 - t(9:22)(q34; q11). This results in part of the ABL proto-oncogene from chromosome 9 being fused with the BCR gene from chromosome 22. The resulting BCR-ABL gene codes for a fusion protein which has tyrosine kinase activity in excess of normal.
Presentation (40-50 years):
Management:
Imatinib:
A 67-year-old man with a 10-year history of gastro-oesophageal reflux disease is investigated for dysphagia. An endoscopy shows an obstructive lesion highly suspicious of oesophageal cancer.
What is the biopsy most likely to show?
Correct Answer C: Oesophageal adenocarcinoma is associated with GORD or Barrett's oesophagus. Metaplastic columnar epithelium would be seen with Barrett's but this is not consistent with the obstructive lesion seen on endoscopy.
Oesophageal cancer:
Until recent times oesophageal cancer was most commonly due to a squamous cell carcinoma but the incidence of adenocarcinoma is rising rapidly. Adenocarcinoma is now the most common type of oesophageal cancer and is more likely to develop in patients with a history of gastro-oesophageal reflux disease (GORD) or Barrett's.
The majority of tumours are in the middle third of the oesophagus.
Risk factors:
A 72-year-old woman is found to have a marked lymphocytosis associated with smudge cells on the blood film. A diagnosis of chronic lymphocytic leukaemia is suspected.
Which one of the following is the investigation of choice?
Correct Answer A: CLL - immunophenotyping is investigation of choice.
Immunophenotyping will demonstrate the cells to be B-cells (CD19 positive). CD5 and CD23 are also characteristically positive in chronic lymphocytic leukaemia.
Chronic lymphocytic leukaemia:
Chronic lymphocytic leukaemia (CLL) is caused by a monoclonal proliferation of well-differentiated lymphocytes which are almost always B-cells (99%).
Features:
Complications:
Investigations:
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