Peter Beitsch, MD
Rakesh Patel, MD

Proper patient selection for APBI is critical to minimize risk of recurrence and complications. However, many healthcare professionals disagree on the specific characteristics that make a patient “suitable” for partial breast radiation.

Among the most controversial topics is using APBI to treat patients with ductal carcinoma in situ (DCIS). Some physicians believe the lack of long-term data on partial breast and DCIS requires a more conservative approach. However, many others believe current data indicates similar outcomes to traditional whole breast radiation, and that unnecessarily restricting access to 5-day radiation therapy can create a significant disadvantage for patients.

Two of the nation’s most renowned brachytherapy experts – surgeon Peter Beitsch, MD and radiation oncologist Rakesh Patel, MD – offer their insights on treating DCIS patients with accelerated partial breast irradiation.

What is your stance on treating DCIS patients with APBI?

Patel: I believe that favorable DCIS patients are excellent candidates for APBI and I treat them routinely in my practice. I treat them as often as patients with invasive ductal carcinoma (IDC). Approximately two-thirds of the patients I see in our clinics undergo breast conserving surgery. Of those who have breast conserving surgery, approximately two-thirds are eligible for APBI. The majority of patients that are good candidates for APBI will strongly consider it as a treatment method.

Beitsch: DCIS is just another kind of breast cancer, and I use the same criteria for determining local and regional treatment as for invasive cancer – negative margins and some upper limit of tumor size. (Though I typically utilize a tumor-to-breast size ratio, rather than a specific size limit, for determining the most appropriate course of treatment.) I treat DCIS patients with APBI as often as I do with invasive cancer.

How do you determine when DCIS patients are suitable for APBI?

Beitsch: I generally take into account the patient’s tumor-to-breast size ratio and age. I am hesitant to offer APBI to women younger than 45, though I have done it for patients as young as 43. In reality, regardless of the radiation method, younger patients will have higher recurrence rates than older women with equivalent histopathologic parameters.

Patel: We try to identify patients at low-risk of having disease outside the target volume. In general, we offer APBI to patients with lesions smaller than 3 cm and negative margins (ideally with a minimum of 2 mm for DCIS).

What are the biggest concerns when treating DCIS with APBI?

Patel: Some older studies suggest that certain subsets of DCIS patients, i.e. younger age, high-grade lesions and close margins, may portend a higher risk of local recurrence relative to even IDC. This is primarily driven by an increased potential of having multifocal disease, which are skip lesions within a single duct system and thus typically in the same quadrant. However, with modern imaging technology, our detection of diffuse calcifications – and thus extensive DCIS or multi-centric disease – has improved, giving us the ability to rule these patients out as candidates for APBI anyway. These patients are actually poor candidates even for a lumpectomy and should most likely receive a mastectomy.

Beitsch: Surgeons and radiation oncologists are both local/regional treating physicians and share similar concerns about local and regional recurrence. While patients with DCIS typically are younger than those with invasive cancer and therefore have a longer event horizon for recurrence, I do not believe the method of radiation matters with regard to local recurrence. I can theoretically envision that brachytherapy has a better local control rate than whole breast irradiation by delivering higher doses to the area at highest risk of recurrence – the lumpectomy bed.

Despite the growing evidence that APBI is effective in treating certain patients with DCIS, why do you think some physicians and groups continue to very conservative about it?

Beitsch: In general, I think it’s because many radiation oncologists think of DCIS as a very different disease than invasive cancer and thus are often more hesitant to treat DCIS with brachytherapy. This kind of thinking is clearly evident in the ASTRO guidelines for APBI patient selection – even with all other parameters being equal, DCIS still falls into the “cautionary” category.

Patel: I think some physicians are more hesitant because the most mature APBI data we have is for patients with stage 1-2 invasive ductal carcinoma, as that was the most common presentation in the late 1990s when APBI was first being investigated. Others continue to await the long-term randomized data for APBI in any subset before expanding their selection criteria. To me, this conservative approach doesn’t necessarily make sense. We should tailor our treatment options to each patient’s clinical, pathologic and personal characteristics rather than adhering to one particular set of stringent guidelines for all patients.

Do you think the hesitancy to treat women with DCIS will restrict access to APBI?

Patel: This could certainly have an impact on the pool of patients that are deemed eligible for APBI. As imaging technology has evolved with digital mammography and MRI, our ability to detect lesions earlier has improved. The result is that we are able to identify a greater proportion of our breast cancers in the early evolution of their disease, meaning we will most likely see an increase in patients with DCIS. Earlier detection should enable these patients to choose more targeted therapies like APBI that have high control rates, better quality of life, improved cosmesis and reduced toxicity – but only if physicians are willing to make APBI available to them.

Beitsch: I think this illogical concern about the nature of DCIS restricts access to APBI. The ASTRO guidelines that place DCIS patients into the cautionary category cause many radiation oncologists to worry that there will be medico-legal liability if they treat a DCIS patient with APBI and the patient experiences a recurrence – despite retrospective research showing the rate of recurrence is the same as with whole breast.

Which set of APBI guidelines do you follow most closely?

Beitsch: I helped construct the ASBS guidelines so I am partial to them; however, they are also the broadest and therefore give us more leeway in patient selection.

Patel: I was one of the contributing authors for the ABS guidelines. The intent was to identify a group of patients that are most substantiated by scientific data and thus they are somewhat intentionally conservative. However, I don’t stick to one set of guidelines in particular. Instead, I recommend the appropriate course of treatment based the individual patient – no single method works for every patient situation.

What other factors are part of your decision to offer APBI to a particular patient?

Patel: I consider clinical and pathologic features, as well as whether the cavity is a suitable size, shape and location for delivering partial breast radiation. It also depends on the patient’s primary goals for the therapy, whether they’re looking for a faster treatment option or a more targeted approach that will result in less skin damage.

Beitsch: Patient preference plays a very important, if not the most important, role in deciding to offer APBI. A majority of patients simply prefer the shortened course of treatment that has significantly less impact on their lives than seven weeks of conventional whole breast radiation.

About Dr. Beitsch & Dr. Patel

Dr. Beitsch is board certified in general surgery but has a special interest in cancer surgery, having completed three additional years of training in surgical oncology at both MD Anderson Cancer Center and the John Wayne Cancer Institute. He is a Fellow of both the Society of Surgical Oncology and the American College of Surgeons. He is co-PI of the American Society of Breast Surgeons Mammosite Registry. He is currently director of the Dallas Breast Center.

Dr. Patel is board certified in radiation oncology with a subspecialty in targeted radiation therapy for breast cancer. He is the 2010-11 president of the American Brachytherapy Society (ABS) and Director of Breast Cancer Services at Western Radiation Oncology, Inc., in Mountain View, California.