Originally published in The Ottawa Citizen January 19, 2004
Original Title: Medical technological advancement redux
Genius… means little more than the faculty of perceiving in an unhabitual way. – William James, 1842-1910
We are living in an exciting age of new therapies and medical technological advancement. This advancement is due to ongoing research and development in areas such as microchip design, medical imaging (e.g. MRI and PET scans), materials science, biological agents, genetics, virology, microbiology, tissue receptor identification, stem cells and nanotechnology among others.
The exponential growth of computing power has enhanced the pace of this research.
New diagnostic tests may improve early detection of cancer, diabetes, heart disease and others. New medical technologies have the potential to supplant or complement standard treatments for these complex diseases. What are some of these exciting developments?
The Ottawa Regional Cancer Centre’s promising research into vaccines to combat specific cancers epitomizes intellectual achievement. The idea is logical and straightforward; alter the structure of a harmless virus and literally teach it to seek out and destroy cancer cells and leave normal cells unharmed. Should the Cancer Centre’s clinical trials prove successful, the vaccine treatment might reduce the dose of chemotherapy medications or eliminate the need for them. The side effects from certain chemotherapeutic agents could be all but eliminated. Morbidity (the harm from the disease and treatment side effects) will be lessened and survival rates will improve. Absolutely marvelous.
The use of radiation to destroy cancerous tumours is a delicate balance of irradiating as much of the tumour as possible while minimizing the dose on adjacent healthy tissue. The most common cause of side effects of radiotherapy is the result of damage to normal tissue. The trick is to find a way to target the cancer with more powerful doses of radiation without the concomitant damage to the surrounding area. If the area exposed to treatment can be reduced, more powerful radiation beams will increase the likelihood of tumor destruction.
In 1946, Robert Wilson, a Cornell physicist postulated that protons (a subatomic particle with a positive electrical charge) could help cancer patients. Forty years of research on the effect of high speed protons is leading to medical applications to combat inoperable cancers.
Proton beam therapy research shows great promise. A cyclotron is used to accelerate the protons to speeds needed to penetrate tissue. The protons can be focused onto a small target area of cells destroying them yet leaving the surrounding tissue unharmed.
It has successfully treated certain brain tumours in children adjacent to the eyes and ears. Other conditions that respond to treatment include malformations of the arteries and veins of the brain that can bleed if left untreated, acoustic neuromas, tumours of the head and neck, medically inoperable non-small cell lung cancer and prostate cancer among others.
There are only three centres in the United States that offer proton beam therapy because of the prohibitive cost of constructing the cyclotron.
Preventive measures to detect early stage colon cancer include colonoscopy, an indispensable and gold-standard procedure. This invasive procedure remains foreboding to many patients. It can be painful and requires pre-test laxatives to empty the bowel. There is a small risk of bleeding or bowel perforation during the procedure.
A recent Chicago meeting of the Radiological Society of North America reviewed a study on the use of 3-D computed tomography (CT) virtual colonoscopy compared to standard colonoscopy when screening for colorectal polyps.
The study compared 1,233 asymptomatic adults (mean age, 57.8 years) who underwent same-day virtual and conventional colonoscopy. Virtual colonoscopy was first performed by the radiologist to check for polyps. The colonoscopy specialist followed with an identical investigation of the colon unaware of the virtual colonoscopy findings.
The term sensitivity for any test refers to the likelihood a positive result is indeed positive. Specificity means the likelihood a negative result is truly negative. As values approach 100 per cent, the more reliable they become.
The sensitivity of 3-D CT virtual colonoscopy for adenomatous polyps was 93.8 per cent for polyps at least ten millimeters in diameter, 93.9 per cent for polyps at least eight millimeters in diameter and 88.7 per cent for polyps at least six millimeters in diameter. Convention colonoscopy produced sensitivities of 87.5 per cent, 91.5 per cent and 92.4 per cent for the three polyp sizes, respectively.
The specificity of virtual colonoscopy for adenomatous polyps was 96 per cent for polyps at least 10 millimeters in diameter, 92.2 per cent for polyps at least 8 millimeters in diameter and 79.6 per cent for polyps at least 6 millimeters in diameter.
“Virtual colonoscopy is a very promising tool for cancer screening because it is minimally invasive and certainly less invasive than conventional colonoscopy,” said lead study author Dr. Perry Pickhardt, an associate professor of radiology at the University of Wisconsin medical school. “It would reduce the number of negative conventional colonoscopies being performed, and also hopefully encourage more patients to seek out screening.”