jayant s vaidya

Data source: http://www.isdscotland.org/isd/servlet/FileBuffer?namedFile=cancer_breast_inc.xls&pContentDispositionType=inline Concept, design, analysis and graphs by Jayant S Vaidya. Submitted for publication. Confidential and not for citation

Women offered screening mammography experience a higher rate of diagnosis of

invasive breast cancer, without a corresponding reduction in subsequent

symptomatic breast cancer.OR in other words,

Many screen-detected invasive cancers would not have grown.

Jayant S Vaidya


Screening mammography aims to detect breast cancer at an earlier more “curable” stage.

Therefore, in the years immediately after screening , the women who have been screened should enjoy a lower incidence of breast cancer.


Data source:

www.isdscotland.org

These graphs are plotted in a rather unusual way


In Scotland, some regions are attended by a screening van for 1 year every 3 years, with no screening occurring in the interim 2 years.

For example, in the regions of Borders, Fife and Forth valley, the screening van –visits every 3 years from 1990, 1991 and 1992, respectively. In Fife, the screening year corresponds most closely to the calendar year


Invasive breast cancer incidence in Fife



Incidence is higher in the screening year because of detection of “earlier” cancers


-

20.0

40.0

60.0

80.0

100.0

120.0

140.0

160.0

180.0

1978

1979

1980

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

Breast Cancer incidence : age standardised rate But the incidence in the interim years is not lowered (compared with that before screening started) Despite the “earlier” detection of cancers in the screening year –the “later” cancers are not


Incidence is higher in the screening year because of detection of “earlier” cancers


Invasive breast cancer incidence in Borders Incidence is higher in the screening year because of detection of “earlier” cancers

But the incidence in the interim years is not lowered (compared with that before screening started) Despite the “earlier” detection of cancers in the screening year –the “later” cancers are not reduced


Invasive breast cancer incidence in Forth valleyIncidence is higher in the screening year because of detection of “earlier” cancers

But the incidence in the interim years is not lowered (compared with that before screening started) Despite the “earlier” detection of cancers in the screening year –the “later” cancers are not reduced

Breast Cancer incidence : age standardised rate


Invasive breast cancer incidence in Scotland

25-29

35-39

45-49

65-69

75-79

85+

Each line represents a single cohort of women



45-4950-55

65-69



45-49

65-69

35-39

25-29

55-59

65-69

85+

75-79

55-59

45-49



25-29

35-39

45-49

35-39

45-4945-49

Incidence of breast cancer in those too young to have screening has remained constant



65-6965-69

Incidence of breast cancer in those too old to have screening has remained constant –this group (light brown line) probably had one round of screening



65-69

25-29

65-69

85+

55-59

This group had the benefit of the whole package of screening for 5 rounds over 15 years

45-49

35-39

45-49



65-69

25-29

65-69

85+

55-59

Screening stopped when they reached the age group of 65-69 between 2001 to 2003

Screening stopped

45-49

35-39

45-49



65-69

45-49

65-69

35-39

25-29

65-69

85+

55-59

45-49

In 2004, despite NOT screening, the incidence remains high – and much higher than that 20, or 10 years ago

Screening stopped


Women who undergo regular screening mammography raise their incidence of invasive breast cancer by 30% to 60%.

In the years between consecutive screens, the incidence is not correspondingly reduced.

And, after stopping screening, rather than enjoying a reduced incidence, these women continue to experience a higher risk of invasive breast cancer

Conclusion


These data demonstrate the dormancy of invasive breast cancer very elegantly, in the real world.

It suggests that a much higher (up to a third) than currently believed proportion invasive breast cancers detected by screening mammography would not have grown .

Further research should focus on studying how so many women manage to keep their invasive cancers in a state of dormancy

Conclusion

jayant s vaidya

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