Cancer Therapy:Where Have We Been and Where We are Going from a Radiation Oncologist’s View John M. Holland, MD Cancer Survivors Day June 9, 2011
Special Thanks to Celine B. Ord, MDOHSU Radiation Medicine Chief Resident
What is cancer?
Significance Cancer is the2nd leading cause of death in United States 1,529,560 new cancers and 569,490 deaths in U.S. in 2010
Edwin Smith Papyrus 1600 BC
Origin of the word “Cancer” 460 BC Credited to Hippocrates, the Father of Medicine Derived from term “carcinos” and “carcinoma” These words often refer to a crab in Greek, because the finger like projections spreading from a cancer cell suggest a crab. Celcus (28- 50BC): Latin- cancer Galen in 130- 200AD: Greek- oncos
Renaissance Period Giovanni Morgagni of Padua 1761
John Hunter 1728-1793
Causes of Cancer Humoral theory of Hippocrates Lymph theory Blastema theory Trauma theory Parasite theory
DNA Proto-oncogenes Tumor suppressor genes
Modern Cancer Treatment Surgery Chemotherapy Radiation
Halsted approach-complete resection of tumor and “arms of the crab” Modern clinical trials demonstrate that less extensive surgery is equally effective Understanding cancer as a disease, better surgical instruments, and combined therapy have enabled surgical progress Fiberoptic technology, laparoscopic, endoscopic thorascopic surgeries-less invasive, less morbidity Evolution of Surgery
Imaging To diagnose cancer, previously required open exploratory surgery Starting in 1970’s. CT, MRI, and PET have improved diagnosis and staging making exploratory surgery less common.
Chemotherapy “Its palliation is a daily task, its cure a fervent hope.” William Castle describing leukemia in 1950 From The Emperor of All Maladies
Chemotherapy for LeukemiaGoodman and Gilman Nitrogen Mustard for Lymphoma
Chemotherapy for LeukemiaSidney Farber Antifolates for Acute Leukemia
Current Therapies Hormonal therapy Chemotherapy Immunotherapy Targeted therapy Radiation therapy
1895 Roentgen discovers x-rays
1896 Becquerel discovers radioactive emissions from uranium compounds
1897 First reported use of x-rays to treat cancer
1898 Curies discover radium and polonium
1899 First reported cure of cancer (basal cell)
1911 Leukemia reported in radiation workers
1928 First international guidelines for radiation safety
1945 Atomic bombs in Hiroshima and Nagasaki
1953 Watson and Crick discover structure of DNA; first linear accelerator made to treat patients
Invention of the Medical Linear Accelerator Karl Brown and Henry Kaplan Stanford Linear Accelerator Center 1950s
Radiation has been an effective tool for treating cancer for over 100 years
More than 60 percent of patients diagnosed with cancer will receive radiation therapy as part of their treatment
Today, more than 1 million cancer patients are treated annually with radiation
Radiation oncologists are cancer specialists who manage cancer patients using radiation for cure or palliation
What is radiation?
Ionizing Radiation can be divided into 2 types:
Electromagnetic Waves (Photons)
Emitted from a radioactive source
Cobalt treatment machine (Cobalt is the radioactive source in the head of the machine)
Photons are generated by a linear accelerator
Protons, neutrons, electrons, heavy pi mesons, alpha particles
How does radiation work? Radiation Damages the Cancer Cell’s DNA
DNA is the critical target of radiation
Radiation can cause both SSBs and DSBs.
Double strand breaks kill cancer cells because they lead to chromosomal aberrations which prevent the cell from dividing normally.
Radiation survival curve
Clinical uses for radiation
Therapeutic radiation serves two major functions
To cure cancer
Destroy tumors that have not spread
Reduce the risk that cancer will return after surgery or chemotherapy
To reduce or palliate symptoms
Shrink tumors affecting quality of life, e.g., a lung tumor causing shortness of breath
Relieve pain by reducing the size of a tumor
Combined Modality Therapy
Radiation with chemotherapy
Radiation and chemotherapy before surgery
Radiation and chemotherapy after surgery
Radiation alone after surgery
Radiation: Where are we now?
Simulation and Immobilization
X-rays, CT scans, PET scans and MRI’s can be taken for treatment planning purposes in the treatment position
Skin marks, including tattoos, can be placed utilizing laser points matched from simulator to accelerator
Simulation and Immobilization
Treatment planning– Image Fusion
Fusion with MRI allows for better tumor definition.
Fusion with PET allows for better tumor localization.
Both allow better targeting of the tumor and less treatment to normal tissues.
Sophisticated software is used to carefully derive an appropriate treatment plan for each patient
Computerized algorithms enable the treatment plan to spare as much healthy tissue as possible
Features of a linear accelerator
Gantry and collimator rotation
Table rotates on pedestal and moves vertically, horizontally, and laterally
Table limit is now over 400 pounds
Machine can produce one or two energies of photons and multiple energies of electrons
Field may be shaped within the gantry using a multileaf collimator (MLC)