Episode 053: Breast Cancer Series, Pt. 2-Fundamentals of Radiation Oncology in Breast Cancer
A critical part of breast cancer management is often the incorporation of radiation therapy. This week, we sat down with our special guest, Dr. Ryan Miller, who is a radiation oncology resident at Thomas Jefferson University Hospital in Philadelphia who shared some super high yield points about how he approaches radiation planning in his patients with breast cancer. Fun fact, you may remember Dr. Miller from Episode 012 when he joined us to talk about the role of radiation in heme/onc emergencies!
What sort of guidance do you provide your patients about the role of radiation?
Landmark study NSABP B-06: Showed importance of radiation in reducing the risk of local recurrence after lumpectomy
Larger meta-analysis suggest that radiation treatment up front has improved overall survival
Do you need any particular imaging prior to their first appointment to assist with your planning?
No particular imaging needs to be done prior to radiation, as lots of imaging will be done as part of diagnosis and surgical planning
During simulation, additional images, analogous to CT without contrast will be taken, but with the patient in the position that they will be treated in, which will help with radiation planning
Part of the simulation process is delineating areas that will be treated called “fields”
For breast cancer, typically treat the whole breast itself
Imaging used to define the borders of the field; usually this is from bottom of clavicular head to a few centimeters below mammary fold; and then medially from mid-sternum to mid-axillary line
In general, what is the total dose and number of fractions that is often standard for patients after lumpectomy? What timeline do you give to these patients?
In earlier studies, the standard dose is 2Gy/day delivered over 25 fractions, for a total of 50Gy
Newer studies are looking at “hypofractionation,” that is giving higher doses each day to shorten the treatment interval to as low as 15-16 fractions
This means that the same total dose of radiation can be given over 3 weeks instead of 5 weeks
Typically, radiation is recommended to start 4-6 weeks after surgery or completion of chemotherapy
What are the common side effects of breast radiation therapy and how do you counsel your patients?
For breast cancer, the side effects are going to be primarily localized to the area
Counsel on skin changes, including redness, irritation, tenderness, swelling, desquamation; these will be cumulative over time, meaning they may not appear at first but may develop halfway through or even after their treatment course is completed
What is a “radiation boost” to the tumor bed?
Radiation boost provides additional radiation to just the surgical cavity, in addition to the more general radiation to the whole breast that the patient gets.
The radiation oncologist can determine the area through placement of wires on the skin and through the placement of surgical clips placed during the lumpectomy
The boost has the potential to limit recurrence even further
Typically 5-8 fractions
Suggested in patients with higher risk disease, including patients with higher grade tumors or those who are younger
This CAN be given at the same time as whole breast irradiation
When do you consider “regional nodal irradiation”?
The idea behind this approach is considering what lymph node areas that breast cancer likes to spread to are and directing radiation to these regions. This includes:
Axilla
Supraclavicular region
Internal mammary region
This can be considered in patients with higher risk disease, including patients with larger tumors, higher grade, LVI, and disease in either the upper inner quadrant or lower inner quadrant (near the internal mammary nodes)
This is becoming used more frequently in patients who are receiving neoadjuvant chemotherapy who therefore do not have lymph node dissections or sentinel lymph node biopsy (SLNB); or in patients who cannot get systemic chemotherapy due to comorbidities. Providing regional nodal irradiation can be of benefit
Side effects:
Axilla: Primary skin toxicity
Supraclavicular area: Mindful of odynophagia or dysphagia since esophagus in close proximity; Monitor thyroid function
Internal mammary: Potential for pulmonary fibrosis and cardiac toxicity
If a patient had a large tumor with positive SLNB, how does this change your radiation planning?
Presence of lymph nodes gives greater push to give regional nodal irradiation, which shows benefit in these patients
In general standard fractionation is used in these patients, but there are some studies investigating hypofractionation
What are your thoughts on the timing of adjuvant chemotherapy and endocrine therapy with radiation? What about HER2-directed therapy?
Radiation is often the last thing in sequence. For instance: (If applicable: Neoadjuvant chemotherapy →) surgery → adjuvant chemotherapy following surgery → radiation will start about 4-6 weeks after surgery/chemotherapy → (if applicable) endocrine therapy
It is safe to give HER2-directed therapy concurrently with radiation, based on data from the KATHERINE study
Are there situations in which you consider radiation to the chest wall and nodal basin if a patient had a mastectomy?
Can be considered in patients following mastectomy if patients had locally advanced disease at presentation
For instance, stage III disease- bulky tumors or LN involvement
Also, if there’s LN disease on post-operative path report
One challenge that radiation oncologists face is in patients who had neoadjuvant chemotherapy and then underwent mastectomy who had achieved complete pathologic response (pCR).
Currently, radiation is indicated, though trials are being done to see outcomes if radiation is eliminated.
What are your thoughts on omitting radiation, for instance, in older patients?
Omission of radiation can be considered but only in very highly specific patients with favorable disease, including smaller tumors, no LN involvement, ER+, HER2-, clean surgical margins
If a patient is ER+ and radiation is omitted, it is critical that they complete endocrine therapy
Also, while omission of radiation may not change overall survival, there is a benefit in terms of local recurrence of disease
Incidence of local breast cancer recurrence at 10 year is 9.5% if radiation is omitted
Improved to 0.9% in group that got radiation
If patients cite frequency of visits as a barrier, radiation oncologists can find a regimen that could work
Is there a role of radiation in ductal carcinoma in situ (DCIS)?
There is a role for radiation to limit local recurrence
Can consider accelerated partial breast irradiation (APBI) or partial breast irradiation (PBI) which is radiation directed at the surgical cavity and the area immediately surrounding it
Smaller region of treatment means better side effect profile
APBI/PBI can be considered in patients with low-intermediate risk DCIS who have at least 2mm negative margins
About our Guest:
A huge thank you to Dr. Ryan Miller (@ryanmillermd) for coming back to join us for another incredible episode! for joining us for this awesome episode. Dr. Miller completed medical school at Cooper Medical School of Rowan University in New Jersey and is a current PGY-6 Radiation Oncology resident at Thomas Jefferson University Medical Center in Philadelphia, PA.
The crew behind the magic:
Show outline: Vivek Patel
Production and hosts: Ronak Mistry, Vivek Patel
Editing: Resonate Recordings
Shownotes: Ronak Mistry
Graphics, social media management: Ronak Mistry
