The Screening Process

The process that an organized breast cancer screening program under-goes to reach its target population for screening can be described in three stages: identification and invitation of the target population; provision of the screening examination; and, if an abnormality is detected, further investigation. Figure 2 illustrates the pathway in more detail.

 

Figure 2
Pathway of a breast cancer screening program

* Breast screening programs obtain final diagnoses from sources such as physicians, pathology reports
and cancer registries.

Organized screening programs began in British Columbia in 1988 and have since expanded to include all provinces, the Yukon and the Northwest Territories.

Women of the target age are recruited to the screening program through either a letter of invitation, a physician referral, or self-referral. At the screening facility, which may be a mobile unit or a fixed site, women receive two-view mammography of each breast. In addition to mammographic screening, women attending programs in Ontario, Manitoba, Nova Scotia, Prince Edward Island, and Newfoundland receive a clinical breast examination performed by a trained health professional while the remaining programs encourage women attending screening to obtain regular clinical breast examination outside of the program from their family physicians (Table 1). All programs provide screening results to both the woman and her physician. If the screening result is normal, women who are still eligible are recalled by letter of invitation for another routine screen. This generally occurs after 2 years, although a minority of women are recalled annually based on age, mammographic results, family history, or other factors that vary across programs. Women with an abnormal screening result are informed, along with their family physician, of the need for further assessment. Generally, the diagnostic follow-up is coordinated by the woman’s physician and is completed when a final diagnosis of either cancer or normal/benign is reached. Program participants are advised that although mammography is highly effective in detecting breast cancers early, there is a possibility that some cancers are undetectable by mammography. A small number of women may develop symptoms in the interval before their next screening visit and are encouraged to consult their physician as soon as possible.

Table 1 Breast cancer screening programs in Canada – usual practices, 1997 and 1998 screen years
Program	Program Start Date	Mammography Interval	Clinical Breast Exam on Site	Target Population Age
British Columbia*	1988	Biennial	No	50-74
Yukon	1990	Biennial	No	50-69
Northwest Territories	1994	Biennial	No	50-69
Alberta	1990	Biennial	No	50-69
Saskatchewan	1990	Biennial	No	50-69
Manitoba	1995	Biennial	Nurse or technologist	50-69
Ontario	1990	Biennial	Nurse	50-69
Quebec	1998	Biennial	No	50-69
New Brunswick	1995	Biennial	No	50-69
Nova Scotia	1991	Biennial	Technologist	50-69
Prince Edward Island	1998	Biennial	Technologist	50-69
Newfoundland	1996	Biennial	Nurse	50-69
* Until mid-1997, British Columbia had annual recall frequency (mammography interval) for all women aged 40 and over.

Table 2 Breast cancer screening program practices for women outside the 50 to 69-year age group, Canada, 1997 and 1998 screen years
Program	Program Practices
	Age Group	Actively Recruit	Accept	Recall
British Columbia*	40-49			Annual
	70-74			Biennial
	75-79			Biennial
	80+		†
Yukon	40-49
	70+
Northwest Territories	40-49			Annual
	70+			Biennial
Alberta	40-49			Biennial
	70-74			Biennial
	75+
Saskatchewan	40-49			N/A
	70+			Biennial
Manitoba**	40-49			Biennial
	70+
Ontario	40-49			N/A
	70+			Biennial
Quebec	40-49		†
	70+		†
New Brunswick	40-49		†
	70+		†
Nova Scotia	40-49			Annual
	70+			Biennial
Prince Edward Island	40-49			Annual
	70-74			Biennial
Newfoundland	40-49			N/A
	70-74			Biennial
* Until mid-1997, British Columbia had annual recall frequency for all women aged 40 and over. ** As of July 1998, both age groups accepted to mobile unit. † Accept with physician referral.

   

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