Oncology is the study and treatment of cancer and tumors. An oncologist is a physician who diagnoses and treats cancer patients. The oncologist sometimes uses chemotherapy, and consults with other physicians to coordinate other methods of cancer treatments for a patient. Cancer patients need to take in to account the likelihood of a cure, or of prolonging life when cure is not possible, the effect of treatment on their symptoms, and the side effects of the treatment. People who are candidates for radiation therapy or anti-cancer drugs need to understand the risks involved with treatment. An oncologist can help to counsel a patient on treatment options and what to expect.

Physicians in this specialty treat patients suffering from numerous diseases and illnesses, but some of the most common are colon cancer, breast disease, spinal cord tumors, melanoma, skin cancer, breast cancer, bone marrow, hodgkin's disease, lymphoma, mesothelioma, sarcoma, lung cancer, leukemia, pancreatic cancer, cervical cancer, liver cancer, mesothelioma cancer (asbestos cancer), brain cancer, acute myeloid leukemia, and bone cancer.

Once properly diagnosed, practitioners can perform numerous procedures on patients including colonoscopy, breast reconstruction, chemotherapy, brachytherapy, cryosurgery, mastectomy, cryotherapy, cabg, breast surgery, surgery, radiotherapy, bone marrow transplantation (bmt), adjuvant therapy, monoclonal antibody treatments, external beam radiotherapy, hormone manipulation, and immunotherapies.

To diagnose patients with possible illnesses and diseases, specialists will often perform one of many tests including biopsy, mri scanning, beta- hcg, ct scanning, x-rays, magnetic resonance imaging (mri), computed axial tomography (ct or cat scan), ultrasound, endoscopy, nse, cea, blood tests, ca 125, tumor markers, beta hcg, positron emission tomography, scintigraphy, psa, and alpha fetoprotein.

Doctor density varies by specialty and location. California has 1,224 practicing oncologists. Broken out by city, oncology doctor density in Anaheim is 15, in Apple Valley is 3, in Arcadia is 8, in Bakersfield is 14, in Berkeley is 21, in Beverly Hills is 16, in Burbank is 6, in Camarillo is 3, in Campbell is 8, in Chico is 3, in Chula Vista is 11, in Concord is 12, in Corona is 12, in Coronado is 4, in Covina is 4, in Duarte is 47, in Encinitas is 10, in Escondido is 9, in Eureka is 3, in Fairfield is 6, in Folsom is 5, in Fountain Valley is 21, in Fremont is 6, in Fresno is 27, in Fullerton is 4, in Gardena is 2, in Gilroy is 2, in Glendale is 20, in Glendora is 12, in Grass Valley is 1, in Hawthorne is 2, in Hemet is 4, in Huntington Beach is 13, in Irvine is 10, in La Mesa is 6, in Laguna Hills is 11, in Lancaster is 5, in Loma Linda is 16, in Lompoc is 3, in Long Beach is 33, in Los Alamitos is 18, in Los Angeles is 182, in Los Gatos is 2, in Manteca is 3, in Mission Viejo is 9, in Modesto is 8, in Montebello is 7, in Monterey is 8, in Monterey Park is 17, in Mountain View is 5, in Newport Beach is 19, in Oakland is 18, in Oceanside is 4, in Orange is 34, in Oroville is 1, in Oxnard is 10, in Palm Springs is 9, in Palo Alto is 65, in Pasadena is 20, in Pleasanton is 10, in Pomona is 13, in Poway is 2, in Rancho Cucamonga is 7, in Rancho Mirage is 14, in Redding is 5, in Redlands is 2, in Redondo Beach is 9, in Redwood City is 8, in Riverside is 19, in Roseville is 7, in Sacramento is 45, in Salinas is 5, in San Bernardino is 8, in San Diego is 76, in San Francisco is 83, in San Gabriel is 5, in San Jose is 20, in San Luis Obispo is 5, in San Mateo is 11, in San Ramon is 5, in Santa Ana is 1, in Santa Barbara is 13, in Santa Maria is 6, in Santa Monica is 27, in Santa Rosa is 14, in Simi Valley is 4, in Sonora is 3, in Stockton is 4, in Sunnyvale is 3, in Thousand Oaks is 7, in Torrance is 26, in Upland is 4, in Vallejo is 11, in Victorville is 1, in Visalia is 4, in Vista is 9, in Walnut Creek is 24, in West Covina is 10, in Westlake Village is 6, and in Whittier is 8.

California’s population is 36,142,137, and it is America’s third largest and most populous state. It also claims the highest and lowest altitudes in the lower 48 states. The lowest point in the country, Death Valley, is also home to the nation’s highest recorded temperature, 134 degrees. Tourists flock to this state for its many outdoor activities and attractions, including Universal Studios, Disneyland, Rodeo Drive shopping, the Golden Gate Bridge in San Francisco, wine country tours, and California’s numerous beaches and parks. Los Angeles is the nation’s second largest city, but California’s capital is Sacramento. The giant sequoias in California’s forests are among the oldest living things in the world, and a redwood in the Redwood National Park is said to be the world’s tallest tree, at 365 feet. California achieved statehood in 1850, and was named the Golden State after the beginning of the Gold Rush in 1848.

According to 2005 Census estimates, California has a population of 36,132,147. Of this population, 9,308,563 are under the age of 18 and 3,827,038 are at or above the age of 65.