(gastro) gastrointestinal cancers Flashcards
define cancer
a disease caused by uncontrollable division of abnormal cells in a specific part of the body
what are the two borad categories of cancer?
1) primary cancers
2) secondary cancers
what is primary cancer?
when the uncontrollable cell division arises directly from the cells of an organ
what is secondary cancer?
spread from a primary cancer from the primary site/organ to another organ either
1) directly
2) indirectly (via blood/lymph)
what is the alternative term for secondary cancers?
metastasis/es
differentiate between primary and secondary cancers
primary = arise from within the cells of the organ itself
secondary = arise as a result of the spread of primary cancers to another organ directly or indirectly
what are the two ways in which a primary cancer can spread?
1) directly to other organs
2) indirectly to other organs VIA blood vessels or lymphatic vessels
name two types of epithelial cells in the GI tract
1) squamous epithelium
2) glandular epithelium
name two types of neuroendocrine cells in the GI tract
1) enteroendocine cells
2) intestinal cells of Cajal
name two types of connective tissue cells in the GI tract
1) smooth muslce
2) adipose tissue
how does cancer of squamous epithelium manifest?
squamous cell carcinoma (SCC)
how does cancer of glandular epithelium manifest?
adenocarcinoma
how does cancer of enteroendocrine cells manifest?
neuroendocrine tumours (NETs)
how does cancer of the intestinal cells of Cajal manifest?
gastrointestinal stromal tumours (GISTs)
how does cancer of the smooth muscle manifest?
leiomyoma OR leiomyosarcomas
how does cancer of the adipose tissue manifest?
liposarcomas
what are GISTs?
gastrointestinal stromal tumours = cancers of the intestinal cells of Cajal
what are liposarcomas?
cancers of the adipose tissue
what are NETs?
neuroendocrine tumours = cancers of the enteroendocrine cells
what are leiomyomas/leiomyosarcomas?
cancers of smooth muscle
where do neuroendocrine cells form?
developm from the neuroendocrine cells in teh body so can occur anywhere, in any organ as neuroendocrine cells are present everywhere
BUT when the occur in enteroendocrine cells of the GI tract = form NETs
what are the divisions of the oesophagus?
cervical oesophagus upper thoracic oesophagus middle thoracic oesophagus lower thoracic oesophagus abdominal oesophagus
which muscle types are present as you progress through the thoracic oesophagus?
upper thoracic = skeletal
middle thoracic = skeletal/smooth
lower thoracic = smooth
which structure divided the lower thoracic oesophagus and the abdominal oesophagus?
oesophagogastric junction
which vertebral levels does the oesophagus run down?
from C6 to T10
what are the two main types of oesophageal cancers?
squamous cell carcinomas (upper 2/3)
adenocarcinomas (lower 1/3)
where do squamous cell carcinomas develop in the oesophagus?
upper 2/3rd of the oesophagus
more common in less developed world
where do adenocarcinomas develop in the oesophagus?
lower 1/3rd of the oesophagus
more common in developed world
why do SCCs develop in the oesophagus?
alcohol consumed is metabolised via the acetaladehyde pathway
resultant acetaldehyde
= potent carcinogen, highly toxic
= causes development of SCC
why do adenocarcinomas develop in the oesophagus?
gastric acid reflux causes (reversible) conversion of normal squamous epithelium into (metaplastic) columnar epithelium
= increases risk of adenocarcinoma formation
what is the acetaldehyde pathway and why is it harmful?
alcohol consumed is metabolised into acetaldehyde by alcohol dehydrogenase
resultant acetaldehyde
= potent carcinogen, highly toxic
from which cells do SCCs arise?
normal squamous epithelium of upper 2/3rd of the oesophagues
from which cells do adenocarcinomas arise?
metaplastic columnar epithelium of the lower 1/3rd of the oesophagus
(formed form gastric acid reflux)
how is the resultant acetaldehyde removed from the body?
metabolised to acetate by aldehyde dehydrogenase and then converted into water and carbon dioxide for easy elimination
how can reflux lead to the development of oesophageal cancer?
repetitive gastric acid reflex = GORD = oesophagitis = Barrett's oesophagus (non-dysplastic, low-grade dysplasia, high-grade dysplasia) = adenocarcinoma
what is oesophagitis?
inflammation of the oesophagus
= commonly caused by GORD
what is Barrett’s oesophagus?
metaplastic changes in the lower oesophagus where the normal squamous epithelium is replaced by columnar epithelium (due to repeat exposure to gastric acid)
has stages =
1) non-dysplastic
2) low-grade dysplasia
3) high-grade dysplasia
what are the stages/progression of Barrett’s oesophagus?
1) non-dysplastic
2) low-grade dysplasia
3) high-grade dysplasia
= ADENOCARCINOMA (either non-invasive or invasive)
define neoplasia
uncontrolled, abnormal growth of cells of tissues
= forms a neoplasm
what percentage of the UK population is affected by GORD and Barrett’s oesophagus?
approx 30% = affected by GORD
5% of GORD patients = affected by Barrett’s
what is the lifetime risk of cancer for Barrett’s oesophagus patients?
approx 0.5-1% of Barrett’s oesophagues patients develop adenocarcinomas
how can Barrett’s oesophagus progress to adenocarcinoma formation?
1) non-dysplastic
2) low-grade dysplasia
3) high-grade dysplasia
= ADENOCARCINOMA (either non-invasive or invasive)
what is recommended surveillance for non-dysplastic Barrett’s oesophagus and why?
endoscopic exploration every 2-3 years
= to look for any metaplastic changes
what is recommended Barrett’s surveillance for low-grade oesophageal dysplasia and why?
endoscopic exploration every 6 months
= to look for any metaplastic changes
what is recommended Barrett’s surveillance for high-grade oesophageal dysplasia and why?
INTERVENTION!
= to prevent progression onto adenocarcinoma stage
why is a biopsy of high-grade oesophageal dysplasia not fully reliable?
very likely that the area biopsied may not have the carcinoma
= cannot assume (!) that carcinoma is not already present elsewhere in the affected region
how common is oesophageal cancer?
the 9th most common cancer
what are the non-modifiable risk factors for oesophageal cancer?
affects the elderly (60+)
males > females
how does oesophageal cancer usually present?
dysphagia & weight loss
= indicative of advanced, late stage disease
how are most people with oesophageal cancer managed?
most people are late stage at diagnosis so = palliative care
(surgery less recommended as the morbidity and mortality rate is very high + surgery is very complex w a low survival rate)
how is oesophageal cancer diagnosed?
1) endoscopy
2) biopsy
how is oesophageal cancer staged?
1) CT scan
2) laparoscopy (to identify intraperitoneal/liver mtastases)
3) EUS = endoscopic ultrasound (to investigate extraluminal neoplasms)
4) PET scan ( to rule out occult metastases)
why is a laparoscopy does to stage oesophageal cancers?
to identify intraperitoneal/liver metastases
why is a EUS (endoscopic ultrasound) does to stage oesophageal cancers?
to investigate extraluminal neoplasms
cannot be seen on CT scan