The connection between regular physical activity — such as walking 30 minutes a day, five days a week — and cancer prevention is documented in hundreds of scientific studies. The reasons include:

• Immune defense. Exercise increases the number of “killer cells” that fight tumors. It also improves resistance to free radicals that damage cells.

• Hormone exposure. Physical activity lowers levels of certain hormones, decreasing the risk of breast, endometrium, ovarian, prostate, and testicular cancer.

To bolster your body’s cancer defense mechanisms, stick with your weekly walking routine. And to help prevent other diseases, such as heart disease and hypertension, make sure you know your numbers, such as cholesterol, blood pressure, and BMI. If you’re a KP member, you can view most lab results via My Health Manager on kp.org.