Radiological Sciences Department Radiotherapy Physics and Equipment RAD 481 Lecture s Title: Introduction Dr. Mohammed EMAM Ph.D., Paris-Sud 11 University Vision :IMC aspires to be a leader in applied medical sciences, health care education and research.
Lecture Outline WHAT IS RADIOTHERAPY AND HOW DOES IT WORK? Mission: IMC is committed to develop highly qualified and competent graduates able to provide leadership and excellence in services to meet the health needs of the nation and the global community through wide range programs, nationally competitive faculty, state-of-the art infrastructure, research applications, and a diverse environment with enriched engagements.
Introduction What is radiotherapy? How does radiotherapy work? When is radiotherapy used? What side effects and complications are associated with the use of radiotherapy? What are the different types of radiotherapy?
What is radiotherapy? The medical use of ionizing radiation in the treatment of malignant cancers. May be used as curative, neo-adjuvant, adjuvant or palliative treatment. Frequently used in combination with other treatment strategies. Types: External Beam Radiotherapy (EBRT) Brachytherapy
How does radiotherapy work? DNA damage to cancer cells Direct damage Indirect damage (via free radical formation) Targeted therapy due to differences between healthy and malignant cells. Major limitation Hypoxia
How is radiotherapy given? Before treatment: CT and simulation. 2D beams using linear accelerator machines from several angles. Aimed at tumour and sometimes the draining lymph node.
How is radiotherapy given? Facilitated by MRI and PET scanning. Dose (measured in Gy) Fractionated. Typical dose 2Gy fractions 5 times a week over a 6-7 week period.
WHEN IS RADIOTHERAPY USED AND WHAT ARE ITS BENEFITS?
When is radiotherapy used? Pre-operative RT Locally advanced disease operable. Rarely used. Post-operative RT Patients with T3 and T4 tumours. 4 positive axillary lymph nodes. Residual disease.
When is radiotherapy used? Post-operative: Minimal tumour bulk following surgery. Minimal effect on wound healing. No delay of surgery. Decreases local recurrence from 10-40% (according to extent of surgery) to <5%. Improves disease-free survival and overall survival.
WHAT ARE RADIOTHERAPY BENEFITS?
What are Radiotherapy Benefits? To reduce the risk of local recurrence following carcinoma of the breast 40%. To treat patients with Ductal Carcinoma of high grade. To treat Mastectomy patients with large, high grade, multifocal tumours involving 4 or more lymph nodes.
When is radiotherapy used? Adjuvant: Following Breast-Conserving Surgery (BCS) or Mastectomy Neo-Adjuvant: Large fungating lesions Radical: Primary incision not possible Palliative: Metastatic disease
When is radiotherapy used? Palliative RT Treatment of symptomatic manifestations. Improves quality of life. Used to treat distant metastases brain, bone, soft tissues. Effective, convenient, cost-effective with tolerable side effects. Can be administered following four cycles of chemotherapy.
WHAT ARE THE SIDE EFFECTS OF RADIOTHERAPY?
Side Effects Acute: Nausea and vomiting Skin desquamation Late: Fibrosis Alopecia Lymphoedema Pneumonitis Cancer Cardiac problems
Late Effect: Radiation Vascular Disease Intimal thickening of arteries and arterioles Dilatation of capillaries and venules Substantial reduction of the capillary vascular bed Ischaemia Fibrosis
Practical problems Potential prolongation of a treatment schedule (Monday-Friday, 3-4 weeks). Radiotherapy planning. Post-operative radiotherapy may have an adverse effect on reconstruction.
WHAT ARE THE DIFFERENT TYPES OF RADIOTHERAPY? External Beam Radiotherapy (EBRT) Internal Radiotherapy (Brachytherapy)
External Beam Radiotherapy Linear accelerators are the most common source Conventional radiotherapy Conformal radiotherapy Intensity-modulated radiotherapy (IMRT)
Internal Radiotherapy (Brachytherapy) Radiation source is placed inside or next to the area requiring treatment Radiation is delivered through catheters or a mammosite balloon device which remains in place for the duration of treatment Can be given after the whole breast has been treated using EBRT, providing a boost Can be used as the sole method of radiotherapy after surgery Limited evidence of clinical advantage
Conclusion Radiotherapy remains a key tool in the treatment of breast cancer and in reducing the incidence of recurrence. Whilst side effects of nausea, vomiting and skin erythema are common, new techniques are reducing toxicity. As research in this field progresses, radiotherapy will undoubtedly continue to improve.
References Sainsbury, JRC; Anderson, TJ; Morgan, DAL. ABC of breast diseases: Breast cancer. BMJ. 2000; 321: 745. Early Breast Cancer Trial Collaborative Group. The Effects of radiotherapy and surgery in early breast cancer: an overview of the randomised trials. N. Engl. J. Med. 1995; 333: 1444-44. Kurtz JM. Radiotherapy for early breast cancer: was a comprehensive overview of trials needed? Lancet. Vol 355: No 9217, 2000; 1739-1740. Fisher B. Bauer M. Margolese R. et al. Five year results of a randomised clinical trial comparing total mastectomy and segmental mastectomy with or without radiation in the treatment of breast cancer. N.Eng. J. Med. 1985; 312: 665-73.
Floor is open for Questions and Discussion Thank you