Emile Grubbe.Not a name typically whispered in a similar breath with pioneers in breast cancer treatment such as Halstead and Beatson! He was however, the first person to use x-rays to treat a patient with breast cancer. In 1896, this medical student was working part time at a factory producing vacuum tubes. He soon developed skin problems and hair loss. His professor, Richard Ludlum, suggested that the invisible rays produced by the tube could have caused the cells in the skin and hair to die. Similarly, he postulated, it may be used to kill cancer cells. He then sent a patient with advanced breast cancer to Grubbe where he wrapped her breast with foil and radiated it with the vacuum tube for 18 consecutive nights. The tumors shrank and the pain abated but the cancer had already metastasized and she died several months later. He went on to become the world’s first professor in roentgenology.
Radiotherapy treatment techniques have evolved dramatically since then and have grown to become an integral part in the management of breast cancer. More so now that we are seeing earlier stage breast cancer with the advent of breast cancer screening. Breast Conservation Surgery (BCS) is typically advocated for early stage breast cancer. Wide excision is followed by 6 weeks of external beam radiotherapy (EBRT). In cases where a mastectomy has been performed, EBRT would be advocated if there are more advanced features in the histological specimen such as size of tumour (>5cm) or number of lymph nodes invovled (≥4 positive nodes).
For the first 5 weeks, the involved breast or chest wall would be encompassed by 2 tangential fields. An additional “supraclavicular” field would be used in patients who have a higher risk of lymph node metastasis. In patients who have undergone BCS, a further one week “boost” to the tumour bed is given. Most patients experience little or no side effects from EBRT at all. In fact the most common complaint is that they have to make the journey to our centre, daily for 5 to 6 weeks! Some do experience skin dryness, erythema and slight tiredness towards the end of the treatment. These acute side effects typically manifest after 2 weeks of treatment and would gradually subside 3-4 weeks after the end of EBRT.
In the past, the use of directly applied orthovoltage fields to the chest wall caused a high incidence of cardiac events which diminished the beneficial effects of EBRT. This effect was recognized by a meta analysis in 2002 by the Early Breast Cancer Trialists’ Collaborative Group (EBCTG). However, the most recent update in 2005 showed that in fact, EBRT not only reduced the local recurrence rate by about two thirds, but a 20% absolute reduction in 5 year local recurrence risk translates to a 5% absolute reduction in 15 year breast cancer mortality. In other words, one breast cancer death could be avoided over the next 15 years for every 4 local recurrences avoided.
In recent years, more sophisticated techniques involving the use of Intensity Modulated Radiation Therapy (IMRT) and Accelerated Partial Breast Irradiation (APBI) have emerged. These techniques have not been thoroughly scrutinized yet but preliminary data has been encouraging. IMRT works by allowing multiple radiation beams to vary in intensity. IMRT equipment divides each beam into multiple, smaller, more focused, pencil-thin beams that precisely target the tumor. In effect, IMRT allows us to shape the doses around our treatment area, delivering maximal dose there, whilst minimizing dose to the surrounding critical structures. The plausibility of using APBI as an alternative to whole breast irradiation is also appealing as treatment time is dramatically shortened to about one week. Several APBI techniques are currently being investigated including intracavitary brachytherapy, intra operative radiotherapy and 3D conformal treatment. Although they are not offered routinely at our centre, they are currently being looked into.
The implications of these new techniques and ideas are huge. We stand at the threshold of new and exciting times for radiotherapy, and cancer management as a whole. With the advent of new technologies and the redefinition of old theories, coupled with modern surgical techniques and new molecular based targeted drugs, we look forward to the day when we can safely eradicate cancer cells without doing any harm to our normal tissue, all in quick and simple measures.
 |
IMRT using multiple fields to treat the chest wall (pink) whilst minimising doses to the critical outlined structures: heart (yellow) and spinal cord (green) |
 |
Comparison of isodose distributions for standard tangential field EBRT against IMRT. Note the uniformity of dose in the IMRT plan and the absence of “hotspots” (red). |
Michael Wang
Consultant
Department of Therapeutic Radiology
National Cancer Centre, Singapore
|
