This study assessed the risk factors for breast cancer development in Indian women. Between 2002-2005, 1866 breast cancer patients and 1873 controls were interviewed to collect data on lifestyle, reproductive history, and anthropometric measurements. For premenopausal women, higher BMI, waist circumference, and body size at younger ages were associated with increased breast cancer risk. Higher levels of physical activity, especially household chores, were linked to lower risk. Among postmenopausal women, larger hip size and body size at younger ages increased risk, while higher physical activity and waist-to-hip ratio reduced risk. The study concluded that anthropometric factors and physical activity influence breast cancer risk in Indian women.

1. Aleyamma Mathew
Additional Professor of Statistics & Epidemiology
Regional Cancer Center, Trivandrum

2. Introduction
• Breast cancer is the commonest female malignancy worldwide with generally
higher incidence in the urban population.
• Positive association between breast cancer risk and augmented anthropometric
factors is reported particularly among postmenopausal women.
• Increased level of physical activity strongly suggested reduced breast cancer
risk.
Objectives
• To assess the risk of anthropometric factors and the level of physical activities
in the development of breast cancer.

3. Materials
• Between 2002-2005, the study was conducted at the Regional Cancer Centre,
Trivandrum and three cancer hospitals in Chennai.
• Cases (n=1866): women with histologically confirmed incident primary breast
cancer.
• Controls (n=1873): age (+ 5 years) and residence (urban/rural) matched women,
who accompanied the cancer patients to the hospital.
• Using in-person interview residence history, menopausal status, reproductive
factors, physical activities, and other confounding variables were collected.
• Anthropometric factors were measured using standard equipments
• Body size at different periods of life (at 10 years, 20 years and the period on the
data was collected) were obtained using pictograms.

4. Methods
• Odds ratios (OR) and 95% confidence intervals (CI) estimated through
unconditional logistic regression models adjusted for age at recruitment, centre,
religion, marital status, education, socio-economic status, residential status, age
at first child birth, parity, duration of breast feeding.
• By scoring the variables, test for linear trend was estimated.
• Multiplicative terms were added to the regression models to test for the
interaction between anthorpometric factors and physical activity.
• ORs were modeled using a linear relationship between anthropometric factors/
physical activity and the log odds of disease.
• Data stratified by menopausal status for the risk analysis.

5. Breast cancer risk according to anthropometric factors
Pre-menopausal
Factors
Case/control (898/1182) OR (95% CI)
Body mass index (kg/m2)
<25
25-29.9
>30
Unknown
560/845
256/268
65/60
17/9
1.00 --
1.32 (1.04-1.67)
1.52 (1.00-2.29)
Waist size (in cm)
< 85
> 85
Unknown
631/918
250/254
17/10
1.00 --
1.12 (0.84-1.49)
Hip size (in cm)
< 100
> 100
Unknown
723/1037
157/135
18/10
1.00 --
1.36 (0.94-1.95)
Waist-to-hip ratio
< 0.85
> 0.85
Unknown
295/398
585/774
18/10
1.00 --
0.97 (0.79-1.20)
adjusted for age, center, religion, marital status, education, socio-economic status, residence status, parity, age at 1st
child birth,
duration of breast feeding and physical activity.

6. Breast cancer risk according to anthropometric factors
Post-menopausal
Factors
Case/control (968/691) OR (95% CI)
Body mass index (kg/m2)
<25
25-29.9
>30
Unknown
559/450
297/185
76/47
36/9
1.00 --
1.27 (0.98-1.64)
1.18 (0.63-1.52)
Waist size (in cm)
< 85
> 85
Unknown
557/486
380/199
31/6
1.00 --
1.22 (0.90-1.66)
Hip size (in cm)
< 100
> 100
Unknown
673/584
264/101
31/6
1.00 --
2.18 (1.50-3.18)
Waist-to-hip ratio
< 0.85
> 0.85
Unknown
261/159
676/526
31/6
1.00 --
0.75 (0.58-0.98)
adjusted for age, center, religion, marital status, education, socio-economic status, residence status, parity, age at 1st
child birth,
duration of breast feeding and physical activity.

7. Breast cancer risk according to Body Size
Pre-menopausal
Factors
Case/control
(898/1182)
OR (95% CI)f
at 10-year : Figure 1
Figure 2
Figure 3 & 4
Figures 5 to 9
329/490
453/572
76/88
40/32
1.00 --
1.12 (0.90-1.38)
1.13 (0.77-1.67)
1.75 (1.01-3.03)
at 20-year: Figures 1+2
Figure 3 + 2
Figures 5 to 9
281/419
424/558
193/205
1.00 --
1.00 (0.80-1.25)
1.16 (0.87-1.54)
Current: Figures 1+2+3
Figures 4 to 9
153/227
745/955
1.00 --
0.90 (0.64-1.25)
adjusted for age, center, religion, marital status, education, socio-economic status, residence status, parity, age at 1st
child birth, duration of breast feeding and physical activity.

8. Breast cancer risk according to Body Size
Post-menopausal
Factors
Case/control (968/691) OR (95% CI)
at 10-year: Figure 1
Figure 2
Figure 3 + 4
Figures 5 to 9
329/236
488/385
110/51
41/19
1.00 --
0.82 (0.63-1.05)
1.26 (0.83-1.92)
1.26 (0.67-2.40)
at 20-year: Figures 1+2
Figure 3 + 4
Figures 5 to 9
276/203
424/348
268/140
1.00 --
0.82 (0.63-1.06)
1.23 (0.90-1.70)
Current: Figures 1+2+3
Figures 4 to 9
163/156
805/535
1.00 --
1.29 (0.92-1.80)
adjusted for age, center, religion, marital status, education, socio-economic status, residence status, parity, age at 1st
child birth, duration of breast feeding and physical activity.

9. Breast cancer risk according to physical activities
Pre-menopausal
Physical activities
Case/control (n= 898/1182) OR (95% CI)
Total physical activity (in minutes)
< 180
180-239
240-299
300-359
> 360
Trend p-value:
124/103
175/190
216/257
130/257
253/375
0.000001
1.00 --
0.94 (0.63-1.40)
0.80 (0.55-1.17)
0.48 (0.32-0.72)
0.70 (0.48-1.02)
Cleaning the house (dusting,
sweeping) (in minutes)
< 30
30-59
> 60
Trend p-value:
206/217
411/539
281/426
0.00362
1.00 --
0.95 (0.72-1.25)
0.82 (0.60-1.10)
Cooking (in minutes)
< 59
60-89
> 90
Trend p-value:
50/61
278/332
570/789
0.158
1.00 --
1.37 (0.81-2.30)
1.07 (0.64-1.79)
adjusted for age, center, religion, marital status, education, socio-economic status, residence status, parity, age at 1st
child
birth and duration of breast feeding and body mass index.

10. Breast cancer risk according to physical activities
Pre-menopausal
House-hold activities and
occupation Case/control (n= 898/1182) OR (95% CI)f
Washing cloths (without machine)(minutes)
< 30
30-59
> 60
Trend p-value:
100/74
302/333
496/775
0.00001
1.00 --
1.02 (0.68-1.54)
0.82 (0.55-1.22)
Ironing cloths
Nil
Yes
811/1048
87/134
1.00 --
0.65 (0.46-0.91)
Walking(to buy things/errands)(minutes)
Nil
< 30
30- 59
> 60
Trend p-value:
389/436
110/169
271/377
128/200
0.0073
1.00 --
0.78 (0.56-1.08)
0.86 (0.67-1.11)
0.77 (0.56-1.05)
Working in garden
Nil
Yes
813/1040
85/142
1.00 --
0.67 (0.48-0.94)
Carrying water (in minutes)
Nil or < 30
30-59
> 60
Trend p-value:
371/348
214/260
313/574
0.00001
1.00 --
0.89 (0.66-1.20)
0.63 (0.49-0.81)
adjusted for age, center, religion, marital status, education, socio-economic status, residence status, parity, age at 1st
child birth and duration of breast feeding, physical activity & variables in the table (where appropriate).

11. Breast cancer risk according to house-hold activities
Post-menopausal
House-hold activities
Case/control (n=968/691) OR (95% CI)f
Total physical activity (in minutes)
< 180
180-239
240-299
300-359
> 360
Trend p-value
278/122
225/142
205/140
117/133
143/154
0.00001
1.00 --
0.84 (0.59-1.19)
0.77 (0.54-1.09)
0.49 (0.34-0.72)
0.47 (0.35-0.73)
Cleaning the house (dusting,
sweeping) (in minutes)
Nil or < 30
30-59
> 60
Trend p-value
303/175
443/317
222/199
0.00123
1.00 --
1.04 (0.78-1.40)
0.84 (0.59-1.18)
Cooking (in minutes)
Nil or< 59
60-89
> 90
Trend p-value
147/73
330/217
491/401
0.0008
1.00 --
0.96 (0.63-1.44)
0.81 (0.54-1.21)
adjusted for age, center, religion, marital status, education, socio-economic status, residence status, parity, age at 1st
child
birth, duration of breast feeding and body mass index.

12. Breast cancer risk according to house-hold activities
Post-menopausal
House-hold activities
Case/control (n=968/691) OR (95% CI)
Washing cloths (without machine)(minutes)
Nil or < 30
30-59
> 60
Trend p-value
251/76
362/223
355/392
0.0001
1.00 --
0.66 (0.46-0.97)
0.47 (0.32-0.69)
Ironing cloths
Nil
Yes
921/653
47/38
1.00 --
0.84 (0.49-1.45)
Walking (to buy things/errands)(minutes)
Nil
< 30
30- 59
> 60
Trend p-value
447/242
84/98
303/230
134/121
0.00032
1.00 --
0.44 (0.29-0.65)
0.77 (0.57-1.03)
0.66 (0.46-0.95)
Working in garden
Nil
Yes
820/610
148/81
1.00 --
1.11 (0.78-1.58)
Carrying water (in minutes)
Nil or < 30
30-59
> 60
Trend p-value
503/233
231/198
234/260
0.00001
1.00 --
0.80 (0.58-1.10)
0.63 (0.46-0.86)
adjusted for age, center, religion, marital status, education, socio-economic status, residence status, parity, age at 1st
child
birth, duration of breast feeding and body mass index.

13. Conclusion
• A positive association was observed between breast cancer risk and augmented
anthropometric factors in both pre- and post-menopausal women.
• Increased body size at early years of life increased breast cancer risk.
• A strong monotonic inverse association was observed between the risk of breast
cancer and physical activity among post-menopausal women and an inverse
association among pre-menopausal women.

14. Co-authors
1. Dr. B Rajan, Regional Cancer Centre, Trivandrum
2. Dr. Beela Sarah Mathew, Regional Cancer Centre, Trivandrum
3. Dr. V Gajalakshmi, Epidemiologic Research Centre, Chennai
4. Dr. V Kanimozhi, Epidemiologic Research Centre, Chennai
5. Dr. Paul Brennan, International Agency for Research on Cancer
6. Dr. Paolo Boffetta, International Agency for Research on Cancer
Funding: International Agency for Research on Cancer, Lyon, France