History of Radiation Therapy

The use of ionizing radiation in the treatment of cancer has evolved during the past century:
- Since the discovery of x-rays in 1895 by:
  - Wilhelm Conrad Roentgen:
    - A German physicist
- Professor Wilhelm Alexander Freund:
  - Demonstrated the disappearance of a hairy mole with the use of x-rays in 1897:
    - Suggesting a potential role for x-rays in treating human disease
- Antoine Henry Becquerel:
  - Is credited with the discovery of radioactivity:
    - When he found that uranium salts emitted rays:
      - That resembled x-rays in their penetrating power
    - He inadvertently performed the first radiobiology experiments in 1901:
      - After discovering damage to his own skin from a container with radium in his vest pocket
- Marie Skłodowska-Curie:
  - Was fascinated by Becquerel’s findings
    and, along with her husband Pierre:
    - Initiated her landmark work on radioactivity:
      - Leading to the discovery and isolation of radium and polonium (a breakdown product of radium)
- Pierre Curie:
  - Validated Becquerel’s radiobiological experiment by:
    - Deliberately producing a radium burn on his own forearm
- In 1903 Pierre and Marie Curie and Antoine Henry Becquerel:
- Were awarded the Nobel Prize in physics for:
  - “Joint work concerning investigations of the radiation phenomena described by Henri Becquerel”
Marie Curie received a second Nobel Prize in chemistry in 1911:
- “In recognition of her services to the advancement of chemistry by the discovery of the elements radium and polonium:
  - By the isolation of radium and the study of the nature and compounds of this remarkable element
- Marie Curie’s contributions included:
  - The standardization of radioactivity:
    - By quantifying the effects of accurately weighed quantities of pure radium salt in 1911:
      - Which continues to serve as the standard to determine the amount of radioactivity in each source
- During the next few decades:
  - Improved understanding of radiobiology led to the realization that:
    - Radiation response is dependent on oxygenation
    - The fractionation of the radiation dose:
      - Is required for improved efficacy and better tolerance
- In the latter half of the 20th century:
  - New sources of ionizing radiation were discovered, and treatment delivery systems
    increased in sophistication
  - In the past 20 years:
    - Computerized treatment planning and delivery systems have become the
      standard of care
Cell death resulting from ionizing radiation can occur through different mechanisms:
- The most common cause of cell death is:
  - Deoxyribonucleic acid (DNA) damage:
    - Leading to double-stranded breaks
- Radiation-induced DNA damage:
  - Occurs either directly or indirectly:
    - By the generation of highly reactive free
      radicals
  - The living cell can repair many of these radiation-induced DNA breaks:
    - Particularly single-stranded breaks, but
      tumors cannot, eventually leading to cell death:
      - This damaging effect of radiation may not be evident immediately but it occurs
        when the cell attempts to divide
- Clinically, the effect of radiotherapy depends on the complex interaction of a multitude
  of factors
- The therapeutic efficacy of ionizing radiation:
  - In tumors at most head and neck sites has been well documented
- Although control and cure of the disease:
  - Should be the paramount considerations in choosing the type of therapy:
    - These factors must be balanced against the functional compromise and impact on quality of life
- As always, a multidisciplinary approach with close cooperation:
  - Not only among the treating team but also with the patient and the family:
    - Is crucial in choosing therapeutic interventions
In general, patients with tumors that require extensive surgical resection with sacrifice of organs such as the larynx or the base of tongue:
- Are now considered candidates for organ-
  preserving approaches:
  - With use of chemoradiation therapy:
    - Reserving surgery for salvage
Tumors, especially skin cancers:
- That are located in areas that are technically difficult to reconstruct:
  - Also may be treated with primary radiation to achieve optimum posttreatment cosmesis
For early-staged tumors (T1 or T2):
- Single-modality treatment (either surgery or radiation therapy):
  - Is chosen for both the primary tumor and the neck (limited low-volume neck metastases) if appropriate
For advanced tumors:
- Surgery combined with radiation and / or chemotherapy or primary chemoradiotherapy are the preferred treatment modalities
The key factors that influence choice of treatment are shown in Table