Limits...
Breast cancer tumor growth estimated through mammography screening data.

Weedon-Fekjaer H, Lindqvist BH, Vatten LJ, Aalen OO, Tretli S - Breast Cancer Res. (2008)

Bottom Line: The mean time a tumor needed to grow from 10 mm to 20 mm in diameter was estimated as 1.7 years, increasing with age.Compared with previously used Markov models for tumor progression, the applied model gave considerably higher model fit (85% increased predictive power) and provided estimates directly linked to tumor size.There is a large variation in breast cancer tumor growth, with faster growth among younger women.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Etiological Research, Cancer Registry of Norway, Institute of Population-based Cancer Research, Montebello, N-0310 Oslo, Norway. harald.weedon-fekjaer@kreftregisteret.no

ABSTRACT

Introduction: Knowledge of tumor growth is important in the planning and evaluation of screening programs, clinical trials, and epidemiological studies. Studies of tumor growth rates in humans are usually based on small and selected samples. In the present study based on the Norwegian Breast Cancer Screening Program, tumor growth was estimated from a large population using a new estimating procedure/model.

Methods: A likelihood-based estimating procedure was used, where both tumor growth and the screen test sensitivity were modeled as continuously increasing functions of tumor size. The method was applied to cancer incidence and tumor measurement data from 395,188 women aged 50 to 69 years.

Results: Tumor growth varied considerably between subjects, with 5% of tumors taking less than 1.2 months to grow from 10 mm to 20 mm in diameter, and another 5% taking more than 6.3 years. The mean time a tumor needed to grow from 10 mm to 20 mm in diameter was estimated as 1.7 years, increasing with age. The screen test sensitivity was estimated to increase sharply with tumor size, rising from 26% at 5 mm to 91% at 10 mm. Compared with previously used Markov models for tumor progression, the applied model gave considerably higher model fit (85% increased predictive power) and provided estimates directly linked to tumor size.

Conclusion: Screening data with tumor measurements can provide population-based estimates of tumor growth and screen test sensitivity directly linked to tumor size. There is a large variation in breast cancer tumor growth, with faster growth among younger women.

Show MeSH

Related in: MedlinePlus

Illustration of potential use of the new cancer growth model. Age at which screening tumors would have become clinical without screening, by tumor size at the time of screening detection. (a) Screening at 55 years of age. (b) Screening at 65 years of age. (c) Screening at 75 years of age. (d) Screening at 85 years of age. Vertical lines mark the expected time at which 25%, 50% and 75% of the screened women are suspected to have died, based on death rates from Statistics Norway. Panel (c) and (d) are based on the screening test sensitivity and growth estimates from the 60 to 69 years age group.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2481488&req=5

Figure 6: Illustration of potential use of the new cancer growth model. Age at which screening tumors would have become clinical without screening, by tumor size at the time of screening detection. (a) Screening at 55 years of age. (b) Screening at 65 years of age. (c) Screening at 75 years of age. (d) Screening at 85 years of age. Vertical lines mark the expected time at which 25%, 50% and 75% of the screened women are suspected to have died, based on death rates from Statistics Norway. Panel (c) and (d) are based on the screening test sensitivity and growth estimates from the 60 to 69 years age group.

Mentions: Whereas screening with mammography has been related to reduced mortality in several randomized trials [32,38], so-called overdiagnosis remains a controversial topic. Following the conservative definition of the number of overdiagnosed cases as 'the number of women who would not had breast cancer in their life time without participating in mammography screening', our new model can be used to estimate the level of overdiagnosis under different screening designs. As a motivation for further studies, we have estimated the probable age at which screening-detected cancers would have become clinically detected without screening, given one screening examination at different ages. Figure 6 illustrates why screening in higher age groups is controversial, since a large proportion of cancers would never have surfaced in the absence of screening. On the other hand, our estimates indicate that the vast majority of screening cancers in the current NBCSP age group (50 to 69 years) would at one stage been detected clinically without screening. The new method presented here provides a toolbox for estimating this and other central issues related to mammography screening.


Breast cancer tumor growth estimated through mammography screening data.

Weedon-Fekjaer H, Lindqvist BH, Vatten LJ, Aalen OO, Tretli S - Breast Cancer Res. (2008)

Illustration of potential use of the new cancer growth model. Age at which screening tumors would have become clinical without screening, by tumor size at the time of screening detection. (a) Screening at 55 years of age. (b) Screening at 65 years of age. (c) Screening at 75 years of age. (d) Screening at 85 years of age. Vertical lines mark the expected time at which 25%, 50% and 75% of the screened women are suspected to have died, based on death rates from Statistics Norway. Panel (c) and (d) are based on the screening test sensitivity and growth estimates from the 60 to 69 years age group.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2481488&req=5

Figure 6: Illustration of potential use of the new cancer growth model. Age at which screening tumors would have become clinical without screening, by tumor size at the time of screening detection. (a) Screening at 55 years of age. (b) Screening at 65 years of age. (c) Screening at 75 years of age. (d) Screening at 85 years of age. Vertical lines mark the expected time at which 25%, 50% and 75% of the screened women are suspected to have died, based on death rates from Statistics Norway. Panel (c) and (d) are based on the screening test sensitivity and growth estimates from the 60 to 69 years age group.
Mentions: Whereas screening with mammography has been related to reduced mortality in several randomized trials [32,38], so-called overdiagnosis remains a controversial topic. Following the conservative definition of the number of overdiagnosed cases as 'the number of women who would not had breast cancer in their life time without participating in mammography screening', our new model can be used to estimate the level of overdiagnosis under different screening designs. As a motivation for further studies, we have estimated the probable age at which screening-detected cancers would have become clinically detected without screening, given one screening examination at different ages. Figure 6 illustrates why screening in higher age groups is controversial, since a large proportion of cancers would never have surfaced in the absence of screening. On the other hand, our estimates indicate that the vast majority of screening cancers in the current NBCSP age group (50 to 69 years) would at one stage been detected clinically without screening. The new method presented here provides a toolbox for estimating this and other central issues related to mammography screening.

Bottom Line: The mean time a tumor needed to grow from 10 mm to 20 mm in diameter was estimated as 1.7 years, increasing with age.Compared with previously used Markov models for tumor progression, the applied model gave considerably higher model fit (85% increased predictive power) and provided estimates directly linked to tumor size.There is a large variation in breast cancer tumor growth, with faster growth among younger women.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Etiological Research, Cancer Registry of Norway, Institute of Population-based Cancer Research, Montebello, N-0310 Oslo, Norway. harald.weedon-fekjaer@kreftregisteret.no

ABSTRACT

Introduction: Knowledge of tumor growth is important in the planning and evaluation of screening programs, clinical trials, and epidemiological studies. Studies of tumor growth rates in humans are usually based on small and selected samples. In the present study based on the Norwegian Breast Cancer Screening Program, tumor growth was estimated from a large population using a new estimating procedure/model.

Methods: A likelihood-based estimating procedure was used, where both tumor growth and the screen test sensitivity were modeled as continuously increasing functions of tumor size. The method was applied to cancer incidence and tumor measurement data from 395,188 women aged 50 to 69 years.

Results: Tumor growth varied considerably between subjects, with 5% of tumors taking less than 1.2 months to grow from 10 mm to 20 mm in diameter, and another 5% taking more than 6.3 years. The mean time a tumor needed to grow from 10 mm to 20 mm in diameter was estimated as 1.7 years, increasing with age. The screen test sensitivity was estimated to increase sharply with tumor size, rising from 26% at 5 mm to 91% at 10 mm. Compared with previously used Markov models for tumor progression, the applied model gave considerably higher model fit (85% increased predictive power) and provided estimates directly linked to tumor size.

Conclusion: Screening data with tumor measurements can provide population-based estimates of tumor growth and screen test sensitivity directly linked to tumor size. There is a large variation in breast cancer tumor growth, with faster growth among younger women.

Show MeSH
Related in: MedlinePlus