Prospective study on physical activity and risk of in situ breast cancer.
BACKGROUND
Physical activity has been identified as protective factor for invasive breast cancer risk, whereas comparable studies on in situ carcinoma are rare.


METHODS
The study included data from 283,827 women of the multinational European Prospective Investigation into C7ancer and Nutrition (EPIC)-cohort study. Detailed information on different types of physical activity conducted during the prior year, such as occupational, recreational, and household activity, as well as on important cofactors, was assessed at baseline. Adjusted HRs for in situ breast cancer were estimated by Cox proportional hazards models.


RESULTS
During a median follow-up period of 11.7 years, 1,059 incidents of breast carcinoma in situ were identified. In crude and adjusted multivariable models, no associations were found for occupational, household, and recreational physical activity. Furthermore, total physical activity was not associated with risk of in situ breast cancer. Comparing moderately inactive, moderately active, and active participants with inactive study participants resulted in adjusted HRs of 0.99 [95% confidence interval (CI), 0.83-1.19], 0.99 (95% CI, 0.82-1.20), and 1.07 (95% CI, 0.81-1.40), respectively (P value of trend test: 0.788). No inverse associations were found in any substrata defined by age at diagnosis or body mass index (BMI) status.


CONCLUSIONS
In this large prospective study, we did not find any evidence of an association between physical activity and in situ breast cancer risk. If not by chance, the contrast between our results for carcinoma in situ and the recognized inverse association for invasive breast cancer suggests that physical activity may have stronger effects on proliferation and late stage carcinogenesis.
Unit of Physical Activity and Cancer, Divisions of Environmental Epidemiology and Preventive Oncology, German Cancer Research Center-DKFZ, Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany. k.steindorf@dkfz.de
Karen
K
Steindorf
Rebecca
R
Ritte
Anne
A
Tjonneland
Nina Føns
NF
Johnsen
Kim
K
Overvad
Jane Nautrup
JN
Ostergaard
Françoise
F
Clavel-Chapelon
Agnès
A
Fournier
Laure
L
Dossus
Annekatrin
A
Lukanova
Jenny
J
Chang-Claude
Heiner
H
Boeing
Angelika
A
Wientzek
Antonia
A
Trichopoulou
Tina
T
Karapetyan
Dimitrios
D
Trichopoulos
Giovanna
G
Masala
Vittorio
V
Krogh
Amalia
A
Mattiello
Rosario
R
Tumino
Silvia
S
Polidoro
José Ramón
JR
Quirós
Noémie
N
Travier
María-José
MJ
Sánchez
Carmen
C
Navarro
Eva
E
Ardanaz
Pilar
P
Amiano
H Bas
HB
Bueno-de-Mesquita
Fränzel J B
FJ
van Duijnhoven
Evelyn
E
Monninkhof
Anne M
AM
May
Kay-Tee
KT
Khaw
Nick
N
Wareham
Tim J
TJ
Key
Ruth C
RC
Travis
Kristin Benjaminsen
KB
Borch
Veronika
V
Fedirko
Sabina
S
Rinaldi
Isabelle
I
Romieu
Petra A
PA
Wark
Teresa
T
Norat
Elio
E
Riboli
Rudolf
R
Kaaks
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000517:prevention & control; D002278:Carcinoma in Situ / Q000453:epidemiology* / Q000517:prevention & control; D015331:Cohort Studies; D005060:Europe / Q000453:epidemiology; D005260:Female; D006801:Humans; D008875:Middle Aged; D009043:Motor Activity; D015999:Multivariate Analysis; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012307:Risk Factors; D055815:Young Adult