Radiation Dose Given
to Skin Cancer Patients
of skin cancer patients in Ottawa were given lower-than-prescribed doses of radiation
over three years because a hospital employee incorrectly calibrated the radiotherapy
An Ottawa Hospital official said 326 patients who were treated at
the hospital's Civic Campus between November 2004 and November 2007 for basal
cell and squamous cell cancers were affected.
The two skin cancers, unlike
melanoma, rarely metastasize and are primarily the result of overexposure to the
sun. None of the patients is believed to have died as a result of the reduced
therapy, Chris Carruthers, the hospital's chief of staff, said in an interview
are skin cancers which are less serious, less aggressive, usually grow over a
slow time- so that's fortunate." Dr. Carruthers said.
The error wasn't
discovered until last November, when a physicist, as part of an annual inspection
of all the hospital's radiation units, decided to do a more thorough review of
the machine. None of the hospital's other units was affected, Dr. Carruthers said,
and the employee responsible for the error has since retired for an unrelated
says it immediately began an investigation to determine the scope of the underdosing
and later hired a Toronto expert medical reviewer to determine the clinical impact.
all, 640 patients received 1,000 radiation treatments from the machine. The Toronto
expert determined 296 patients were underdosed, 30 fewer than the hospital's own
investigation concluded. The underdosages ranged from 3% below the recommended
amount of radiation to a few as low as 17% below. The normally accepted variation
in dosage is 5% to 7%.
treatment, radiation energy is directed at the cancerous tissue to damage and
destroy genetic material in the cancer cells, which triggers cell death.
Care Ontario, which has been given the Toronto expert's report, has been asked
by the Ottawa Hospital to independently review what happened and make recommendations
to prevent it from happening again.