In Canada in 1993 approximately 1,300 new cases of invasive carcinoma
of the cervix were diagnosed, and about 400 deaths were expected to occur
from this disease. The yearly overall cost of invasive disease and death
in Canada from cervical cancer has been estimated at 180 to 270 million
dollars.
Options
Main screening options were visual inspection, Pap smear, colposcopy/cervicography,
HPV group-specific antigen, DNA probe, dot blot or Southern blot, or polymerase
chain reaction. Treatment options included physical or chemically destructive
agents (conization, cryosurgery, lasers, salicylic acid, cantharidin, bi-
and trichloroacetic acid) and chemotherapeutic agents (podophyllin, 5-fluorouacil,
bleomycin).
Outcomes
Test sensitivity and specificity; cure (e.g., complete clearing of
warts) and recurrence rates.
Evidence
MEDLINE was searched for 1966 to June 1993 using the keywords "papillomavirus",
"cervix neoplasms", "mass screening", "prospective studies", "prevalence",
"sensitivity", "specificity", "human", and "female".
Values
The 13-member Task Force of experts in family medicine, geriatric medicine,
pediatrics, psychiatry and epidemiology used an evidence-based method for
evaluating the effectiveness of preventive health care interventions. Recommendations
were not based on cost-effectiveness of options. Patient preferences were
not discussed.
Background papers providing critical appraisal of the evidence and tentative
recommendations prepared by the chapter author were pre-circulated to the
members. Evidence for this topic was presented and deliberated upon in
1- to 2-day meetings, 2 to 3 times per year from January 1993 to June 1993.
Consensus was reached on final recommendations.
Benefits, Harms, and Costs
In general, available tests have poor sensitivity and specificity,
and are invasive and costly. Test characteristics are summarized below.
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(range of 19% to 52%) |
(50% in one study) |
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(significant false positive rate) |
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The natural history of HPV is not well understood. Comparison between
studies is difficult because of differences in reported outcomes. An RCT
of Podophyllotoxin therapy reported complete clearing of penile warts in
53% of 34 patients, but 100% recurrence in patients who returned for 16
week follow-up. Most studies with sufficient follow-up report high recurrence
rates. RCTs with interferon and CO2 laser vaporization found
better cure rates. However, recurrence rates remained high, and good cure
rates were also found in untreated patients. Currently, no therapy exists
for latent HPV infection. Thus, the value of screening is unknown. Potential
adverse effects of screening include test- and treatment-related morbidity,
labelling, increased costs and therapeutic load.
Recommendations
Recommendation grade [A, B, C, D, E] and level of evidence
[I, II-1, II-2, II-3, III] are indicated after each recommendation. Citations
in support of individual recommendations are identified in the guideline
text.