April 12, 2013

Today, we will be discussing esophageal and pancreatic cancers.

• Esophageal cancer

1.      Barrett’s esophagus: a change of cells in the distal esophagus from stratified squamous epithelium to columnar epithelium due to reflux.

2.      Adenocarcinoma for distal 1/3 and squamous cell carcinoma for proximal 2/3

3.      Presenting symptoms:  dysphagia and weight loss.  Complain of food sticking in throat or chest, difficulty swallowing, and Odynophagia (painful swallowing).

• Treatment techniques

1.      Treatment is complex and difficult due to locally advanced disease typical at time of diagnosis.

2.      Primary goal is to provide relief of dysphagia and a chance for cure.

3.      Surgery is high-risk and mortality rates range from 8-31%, and even after a curative resection, most patients fail distantly with lung, liver, or bone metastasis.

4.      Radiation with chemo is the standard treatment of choice.

• Field design

1.      Spreads longitudinally with skip lesions up to how many cm from the primary tumor?  They can be up to 5cm away from the primary lesion.

2.      Regional spread to draining lymphatics is common early – the cervical, supraclavicular, mediastinal, and subdiaphragmatic node regions are at risk, depending on primary tumor location.

3.      Portals encompassing areas at risk are usually large.

• Dosing

1.      Standard technique for treating the initial large field is AP/PA followed by shrinking fields of various arrangements (ex. oblique off-cord).

2.      For treatment with radiation alone, dose is 65Gy; with chemo, dose is 5040cGy.

3.      Both doses exceed the tissue-tolerance of the spinal cord and careful dosimetric planning is necessary.

4.      What structures affect lateral treatment doses within the thorax?  The lungs and the heart affect treatment doses.

• Simulation & positioning

1.      Prone position uses gravity to help place the esophagus at a greater distance from the spinal cord

2.      Supine position is easier for elderly or severely ill patients to hold for a long time.

3.      Vac-locks for arms above head.

4.      Oral contrast may be given 30 min before scan.

5.      A pudding-like contrast may also be given at the time of simulation to help visualize esophagus.

6.      Which patients may not tolerate oral contrasts, especially in supine position?  Patients with dysphagia or odynophagia may not tolerate oral contrasts.

• Side effects

1.      After 2 weeks patients begin to experience esophagitis; patients complain of substernal pain when swallowing and the sensation of food sticking in their esophagus.

2.      May need to be on a modified soft or pureed diet.

3.       High-calorie liquid meal supplements like Carnation Instant Breakfast, Boost, or Ensure are good alternatives.

4.      Esophagitis can become severe by end of treatment and may require placement of a nasogastric tube or PEG tube – What are these?  A nasogastric tube that goes through the nose down to the stomach; it is a feeding tube.  The PEG tube is a surgically inserted tube from abdominal wall to stomach.

5.      When with chemo, esophagitis is worse; plus decreased blood counts, nausea and vomiting are common.

6.      Radiation pneumonitis or pericarditis may occur if large volume of lung or heart is in the field.

7.      Perforation and fistula formation can occur from rapid shrinkage of a tumor that was adherent to the esophageal/tracheal wall.

• Long-term effects:

1.      Stenosis or stricture as a result of scar formation.

2.      Transverse myelitis – shouldn’t occur if treatment is planned and delivered precisely.

• Pancreatic cancer

1.      Fourth leading cause of cancer deaths.  High mortality rate, considered one of the most deadly cancers.

2.      Risks: unknown, but smoking is definitely associated.

3.      Presenting symptoms: jaundice, abdominal pain, anorexia, and weight loss.

4.      Occur most frequently in head and neck of the pancreas as adenocarcinoma.

• Treatment techniques

1.      Surgery is the treatment of choice, but most tumors are unresectable.

2.      Most common potentially curative surgical procedure is the pancreaticoduodenectomy.

3.      What is the more common name for this surgery?  Whipple procedure.

4.      Even with a potentially curative resection, the 5-year survival rate is usually less than 10% with a median survival time of 11-14 months.

5.      Main method is radiation plus chemo, especially for locally advanced or unresectable tumors.

• Field design & dosing

1.      AP/PA for primary tumor bed and draining lymphatics.

2.      Dose of45 Gy, and up to 50Gy if reduce field size at 45Gy – What is important about 45Gy here?  Small bowel TD 5/5 is 45Gy.

3.      Dose through lateral fields is limited to 18-20Gy because of the large volume of liver and kidneys in these fields.

4.      Critical structures include kidneys, liver, small bowel, stomach, and spinal cord.

5.      For treating a head of pancreas lesion, approx. 50% of the right kidney is in the treatment volume; at least 2/3 of left kidney must be shielded to preserve normal kidney function.

• Simulation & positioning

1.      Supine with arms above head.

2.      Oral contrast given 30-60 minutes before scan.

• Side effects

1.      Most common are nausea and vomiting.

2.      Other potential acute effects are leukopenia, thrombocytopenia, diarrhea, and stomatitis.

3.      Long-term effects, including renal failure, are rare.

Reflections:
http://www.nutraingredients-usa.com/Health/Cancer-risk-reduction/Middle-Eastern-herb-shows-potential-against-pancreatic-cancer
This is a link to a study on thymoquinone (antioxidant from black cumin seed) and its effects on pancreatic cancer patients.  Animals received xenografts of pancreatic cancer.  After treatment with the thymoquinone extract, 67 percent of the animals with the pancreatic cancer had their cancer shrink significantly.  Also, the herb is safe when used in moderation.  Middle Eastern and Asian countries have been using its oil for thousands of years with no reported toxic effects.