National Cancer Act of 2003

Amends the Public Health Service Act to fund prevention, detection, and treatment programs of the National Cancer Institute, including translational cancer research (research needed to transform scientific discoveries into approaches and products to treat and cure cancer). Directs the Secretary of Health and Human Services to carry out a research grant program to fund projects that seek to develop cancer treatments that target cancer cells.

Addresses issues of cancer care, including: (1) clinical trial participation; (2) workforce needs; (3) cancer survivorship; (4) cancer care guidelines; (5) the supply of researchers; (6) a colorectal cancer screening demonstration program; and (7) an Institute of Medicine study on whether to provide medical coverage under title XVIII (Medicare) of the Social Security Act to certain cancer patients.

Directs the Commissioner of Food and Drugs to submit to Congress a plan outlining steps to accelerate the process for reviewing and approving new cancer drugs and treatments.

Requires health insurance plans covered by the Public Health Service Act and the Employee Retirement Income Security Act of 1974 to provide: (1) coverage for clinical trials; (2) coverage of cancer screening, including tobacco and nutrition counseling and genetic testing; and (3) patient access to benefit information.

Addresses issues of managing physicians and quality of care for cancer patients covered by such plans, including designating a lead managing physician.

Amends the Public Health Service Act to authorize the Secretary of Health and Human Services, acting through the Administrator of the Health Resources and Services Administration, to make grants for: (1) model programs to provide services for cancer and chronic diseases to individuals of health disparity populations; and (2) patient navigators for managing such care of such individuals.