FORT LAUDERDALE, Fla--The National Comprehensive Cancer Network (NCCN), a consortium of 16 leading US cancer centers, has ventured into the contentious area of breast cancer screening, and in its first draft, the breast cancer screening committee has recommended annual mammography screening for all women age 40 and over.
In a presentation at the NCCNs third annual conference, committee member S. Eva Singletary, MD, of M.D. Anderson Cancer Center, said that "the key to improving morbidity and mortality of breast cancer is early, accurate diagnosis." She added, however, that cost effectiveness is a critical element of screening procedures and must play a major role in deciding how best to use existing technology.
"One of the first decisions that our committee had to make was the starting point," Dr. Singletary said, "and we felt strongly that the starting point should be the physical examination, because when we talk about breast screening, it does not mean mammography as a stand-alone procedure."
The committee agreed that the decision to proceed with screening mammog-raphy is contingent upon the results of the physical exam, which is the primary element in the practice guideline decision tree.
In the absence of suspicious findings on physical exam, decisions on whether to proceed with screening mammography are based on risk stratification, with women falling into one of four groups.
- For women ages 20 to 39, the guideline states that physical breast examination should be repeated every 3 years.
- For women age 40 and above, the guideline recommends an annual physical examination and annual mammog-raphy. "This decision," Dr. Singletary pointed out, "is based on the consensus of the American Cancer Society." The committee also noted among its "breast cancer considerations" that "mammog-raphy interval and cost effectiveness are controversial in the 40 to 49 age group."
- Otherwise healthy women 25 years of age or older who have received thoracic radiotherapy should undergo annual mammography and physical examination every 6 months, beginning 10 years after their thoracic radiotherapy.
Said Dr. Singletary: "We based our data on the results from the Late Effects Study Group, whose findings were that women who received thoracic radiation in their second or third decade had a risk of developing breast cancer as high as 35% by age 40."
- Annual mammography and physical examination every 6 months are also advised for women 25 years of age or older who are genetically predisposed to develop breast cancer. This screening schedule should begin when the womans age is 5 to 10 years below that of the earliest index case in her family.
Abnormal Physical Exam
The guideline assigns women who present with suspicious findings on physical examination to one of four categories--a dominant mass, nipple discharge, thickening or nodularity of the breast, and skin changes. Therese Bevers, MD, also of M.D. Anderson Cancer Center, presented separate decision-making pathways for each of these categories.
Women presenting with a dominant mass are further categorized according to age. Separate guidelines for initial and follow-up evaluations were written for women younger than 30 years of age and those aged 30 and older. This is also the case for women who present with any thickening or nodularity of the breast.
Follow-up evaluation for women with nipple discharge and no palpable mass is based on the characteristics of the discharge. "The most worrisome kind of discharge is that which is persistent, spontaneous, unilateral, from a single duct, and serous, sanguineous, or serosanguin-eous," Dr. Bevers said. "These patients," she continued, "are of great concern, and appropriate evaluation should begin with a diagnostic mammogram."
For women who present with skin changes, bilateral diagnostic mammog-raphy with or without ultrasound is recommended, with further evaluation determined according to the results. "If the skin biopsy is malignant," Dr. Bevers said, "we would obviously place the patient on the appropriate NCCN guideline." However, if the biopsy does not show malignancy, further diagnostic workup is warranted, since inflammatory breast cancer can be difficult to evaluate.
Luz Venta, MD, of Northwestern University/Lurie Comprehensive Cancer Center, outlined the NCCNs practice guideline for screening mammography. She emphasized that the guideline refers only to screening studies "and is applicable only to patients who are totally asymptomatic."
If screening mammography reveals no abnormalities, follow-up consists of continued routine screening and physical examination in accordance with the guideline for physical examination.
If results of a screening mammography are somewhat abnormal, but not highly suspicious, the results should be compared with prior images. "If there is still a question on the mammogram as to whether the finding is clearly benign, then a diagnostic mammogram, with or without ultrasound, should be performed," Dr. Venta advised.
In the NCCN guideline, results of diagnostic mammograms are categorized according to the American College of Radiologys Breast Imaging Reporting and Data System (BI-RADS). Findings are classified as negative, benign, probably benign, suspicious, or highly suggestive of malignancy.
"The purpose of putting findings into categories according to BI-RADS," Dr. Venta said, "is so that all radiologists will uniformly report mammograms in the same way, and also to permit us to attach a recommendation for follow-up to each of these categories."
If findings are negative for disease or clearly benign, patients continue with routine screening. If findings are probably benign, additional mammograms should be performed every 4 to 6 months for a period of 2 to 4 years. Biopsy may be indicated if a patient is noncompliant or highly anxious about the results. If results are suspicious or highly suggestive of malignancy, tissue biopsy is recommended with appropriate follow-up.
Panel moderator Paul Engstrom, MD, of Fox Chase Cancer Center, pointed out that breast cancer screening is not without controversy and "is littered by consensus conference proclamations, specialty group pronouncements, and managed care opinions." He noted, however, that screening is becoming increasingly important for evaluating women suspected of having disease, those who have symptoms, and those at high risk. The NCCN guideline, he concluded, can add to the existing knowledge base and shed new light on this topic.