Preventive Cancer Screening and Vaccination
Screening means checking your body for cancer before there are signs or symptoms of the disease. The routine performance of screening tests may find many kinds of cancer early, when treatment is likely to work best.

Screening for Breast, Cervical, and Colon Cancers
CDC supports screening for breast, cervical, and colorectal (colon) cancers as recommended by the U.S. Preventive Services Task Force.

Free or Low-Cost Mammogram or
Pap Test
To find out if you qualify, call your local program.  
 
Breast Cancer
Currently, the best way to find breast cancer is with a mammogram. Mammograms are the best method to detect breast cancer early when it is easier to treat. 

Cervical Cancer
The Pap test can find abnormal cells in the cervix which may turn into cancer. Pap tests can also find cervical cancer early, when the chance of being cured is very high. 

The U.S. Food and Drug Administration approved a human papillomavirus (HPV) vaccine for females aged 9–26 to prevent cervical cancer. However, the HPV vaccine does not substitute for routine cervical cancer screening (Pap tests), according to recommended screening guidelines.

 Colorectal (Colon) Cancer
Colorectal cancer almost always develops from precancerous polyps (abnormal growths) in the colon or rectum. Screening tests can find precancerous polyps, so that they can be removed before they turn into cancer. Screening tests can also find colorectal cancer early, when treatment works best. 

The Colorectal Cancer Screening Demonstration Program offers free or low-cost screening at five sites.

Screening for Lung, Ovarian, Prostate, and Skin Cancers
Screening for lung, ovarian, prostate, and skin cancers has not been shown to reduce deaths from those cancers.

Lung Cancer
Scientists have studied several types of screening tests for lung cancer. A review of these studies by experts shows that more information is needed. It is not known if these tests can help prevent deaths from lung cancer. 
There is no evidence that any screening test reduces deaths from ovarian cancer.

Prostate Cancer
Because current evidence is insufficient to determine whether the potential benefits of prostate cancer screening outweigh important harms, there is no scientific consensus that such screening is beneficial. 

Skin Cancer
The U.S. Preventive Services Task Force has concluded that there is not enough evidence to recommend for or against routine screening (total-body examination by a clinician) to detect skin cancers early. 

http://www.jktd.org/Article/2007/1507.html