the availability of screening in developed
countries and its effectiveness in decreasing cervical
cancer incidence and mortality, some women are inadequately
screened. Women who are not screened at the recommended
interval have a higher risk of developing cervical
cancer and are more frequently diagnosed at an advanced
stage.1–3 Reasons women give for not participating in cervical
screening include a lack of knowledge about the Pap test,
believing screening is of no benefit, considering oneself not at
risk of cervical cancer, and fear of embarrassment or pain.4
These reasons are often related to socioeconomic status, ethnicity,
age, health status, and access to the health care system.4
Several strategies have been used to reach these women
including small media, mass media, group education, one-onone
education, and invitation letters.5 Invitation letters are
used by organized cervical cancer screening programs to encourage
participation.6–9 Within Canada, cervical screening
invitation letters have been used on a limited basis and have
not been evaluated using a population-wide, randomized
controlled trial (RCT). Although the province of Manitoba has
used various community-level interventions to improve
screening, one-third of Manitoba women have not had a Pap
test in the previous 3 years and 10% have no Pap test record
in the 12-year-old screening registry.10
In order to increase participation, the provincial screening
program decided to mail invitation letters to unscreened
Manitoba women 30 to 69 years of age. Unscreened women
were chosen because the risk of invasive cervical cancer is
greater in women who have not been screened and increases
with the amount of time since the last Pap test.11 The purpose
of this study was to evaluate the effectiveness of an invitation
letter on cervical screening participation among unscreened
women. The primary outcome was whether or not a woman
had a Pap test in the 6 months following an invitation letter.