OCCULT CANCER of BREAST POST LUMPECTOMY

Abstract

Objective. The purpose of this study was to investigate the efficacy of ultrasonography in detecting an occult malignancy after surgery for breast cancer and to assess the imaging and clinical findings associated with a recurrence. Methods. During a 4-year period, 3329 bilateral whole-breast ultrasonographic examinations were performed to detect occult malignancies clinically and mammographically in 1968 asymptomatic patients after breast cancer surgery. All questionable lesions were confirmed with ultrasonographically guided intervention. This study reviewed ultrasonographic findings and pathologic results of the questionable lesions along with the clinical parameters of the patients. We searched for false-negative cases from the hospital database. Results. Among the 1968 patients, ultrasonography revealed questionable lesions in 57 (2.9%). The questionable lesions were lymph nodes in 42 and masses in 15; of these lesions, 24 were malignant (true-positive) and 33 were benign (false-positive). Ten false-negative cases were identified. The sensitivity and specificity were 70.6% and 98.3%, respectively. The locations of the recurrent lesions were the regional lymph nodes in 14 cases (4, axillary fossa; 4, interpectoral; 4, internal mammary; and 2, supraclavicular lymph nodes) and the breast and mastectomy bed in 7 cases. The mean size of the malignant lymph nodes was larger than that of the benign lymph nodes. Among those with positive examination results, the clinical parameters in the recurrent and nonrecurrent groups were similar. Conclusions. Postoperative follow-up ultrasonography showed occult malignancies clinically and mammographically in 1.2% of the patients who had been treated for breast cancer. Familiarity with the common location of a tumor recurrence is essential for making an accurate ultrasonographic evaluation in these patients.

Most clinicians use mammography to screen women who have been treated previously for breast cancer. Although it has been reported that breast ultrasonography is the best imaging method for evaluating the chest wall and the axilla, which cannot be visualized on mammograms,¹ the routine use of ultrasonography is usually limited, with the exception of characterizing palpable lesions or mammographic abnormalities in treated breasts. Several reports have shown that ultrasonography can contribute to the detection of occult malignancies clinically and mammographically in asymptomatic women with dense breast tissue.^2,3

Considering that a history of breast cancer is one of the major risk factors for recurrence, it is believed that breast ultrasonography is more valuable for the early detection of an occult new primary malignancy and for identifying a recurrence in asymptomatic patients who had surgery for breast cancer than it is in those who have not had breast cancer. Previous reports have also suggested that early detection of a recurrence is better for the treatment of the patient, although no data have shown an improvement in overall survival rates.^1,4 The aim of this study was to investigate the efficacy of breast ultrasonography for the detection of occult malignancies clinically and mammographically during the postoperative follow-up of breast cancer and to assess the ultrasonographic and clinical findings associated with a recurrence.

Discussion

A follow-up of patients with breast cancer is an integral part of the treatment in most breast oncology centers, but there have been no standardized programs until recently. Although even a close follow-up with intensive investigations has not led to improved postoperative survival, there is a prevailing belief among both patients and clinicians that if a recurrence is detected early, when tumor burden is low, there is a greater likelihood of controlling the disease and improving the quality of life and, possibly, overall survival. There are definite disadvantages, however, of a close follow-up, including increased patient anxiety, excessive cost and physician time, and false-positive and -negative results. Indeed, only 14% of all recurrences have been reported to be asymptomatic.⁶

To date, surveillance mammograms are routinely included in various follow-up programs for breast cancer, but investigations into the effect of other imaging modalities have not been performed widely. Balu-Maestro et al⁷ reported that tumor recurrences were identified in 95.5% of cases by mammography, 90.9% by ultrasonography, and 45.5% by a physical examination. Mammography in a treated breast is less sensitive than in an untreated breast because of poor visibility of the lesions situated deep in the muscle layer, some distance from the scar, or in the axilla,¹ and the mammographic examination itself is more uncomfortable. In our experience, ultrasonography is a useful surveillance method that can overcome the limitations and discomfort associated with a mammogram in those patients treated for breast cancer. Magnetic resonance imaging is known to be a highly sensitive modality for the recurrence of breast cancer⁸; however, ultrasonography is more beneficial because of its high specificity, widespread availability, easily accessible biopsy procedures, comfort, and lower cost. In our community, it costs approximately $120 for bilateral breast ultrasonography and $160 for an ultrasonographically guided breast biopsy, whereas it costs $580 for contrast-enhanced breast magnetic resonance imaging.

In this study, it was shown that ultrasonography was effective clinically and mammographically for the detection of an occult malignancy in the asymptomatic patients after breast cancer surgery. These malignancies were observed more frequently as lymphadenopathy. We do not believe that these results are representative of all postoperative recurrences. This study was designed to be focused on nonpalpable recurrences. It is important to know which area to carefully evaluate during postoperative breast ultrasonography in patients and which findings are more likely to be verified as a recurrence. Although the overall survival rate after the detection of a local recurrence is poor (21% to 36% at 5 years) and the prevalence of a distant metastasis is high (45% to 90%), a recurrence is not necessarily a sign of a systemic metastasis and a poor prognosis.⁹ Of the 21 recurrent patients, 7 (33%) showed other organ metastases, but all of them were still alive.

There were 10 cases with false-negative ultrasonographic findings. In 5 (50%), the internal mammary and supraclavicular lymph nodes were overlooked, and in 4, local recurrences, which were revealed to be isolated microcalcifications on mammography and were pathologically diagnosed as DCIS, could not be identified. Ultrasonography does not show microcalcifications well. Of the occult malignancies shown by ultrasonography in this study, there was no case with microcalcifications on mammography. Although several limitations with ultrasonography have been reported in a conservatively treated breast, such as parenchymal scarring mimicking or concealing a carcinoma,¹⁰ upgraded ultrasonographic scanners can depict the ultrasonographically questionable lesions. The smallest one detected was 0.5 cm, and no cases with false-negative results, which were locally recurrent near the conserving surgery scar, were found except for a skin lesion.

The resulting 1.2% cancer detection rate in this study is slightly higher than that reported for screening mammography,^11–,¹³ as well as that for screening ultrasonography in previous studies in a healthy population.^2,3 These malignancies may have gone undetected until the patients’ follow-up visit, unless they appeared palpable in the interval between the follow-up examinations.

Recht et al¹⁴ studied the time course of treatment failure after breast-conserving surgery and irradiation and showed that the risk of ipsilateral breast recurrences peaks at a rate of 2.5% per year between 2 and 6 years after treatment, and then the risk of recurrent breast cancer decreases; however, patients remain at risk even 10 years after therapy.^14–,¹⁶ In this study, the longest postoperative duration was 9 years, the shortest duration of the recurrence after surgery was 8 months, and the mean postoperative duration was 36 months; therefore, a periodic ultrasonographic evaluation, starting from the sixth postoperative month to up to at least 3 years is believed to be necessary.

Concerning the questionable lesion on ultrasonography, although this study investigated whether the clinical parameters related to a recurrence were present to lower the rate of unnecessary ultrasonographically guided interventions, no statistically significant difference was found in the current group except for the larger size of the lymph node in the recurrent group. Although there is some concern about the small increase in the local recurrence rate after breast-conserving surgery or the sentinel node biopsy technique,^17,18 no cases of recurrence had a sentinel node biopsy in our series.

This study had several limitations. The positive biopsy rate of the ultrasonographically guided intervention was somewhat low (42.1%). It is possible that such an intensive investigation may lead to unnecessary invasive procedures resulting in increased medical cost and patient anxiety, but the immediate verification can prevent undertreatment in a high-risk group. Furthermore, the imaging findings had overlapping features. A recurrent case showed a 0.5-cm, round, cystlike, hypoechoic mass at the mastectomy bed on ultrasonography (Figure 2⇑). In general, even if the lesion appears benign, if it is new in the postoperative patient, efforts must be made to obtain a histologic diagnosis. Second, this long-term follow-up was not linked with other institutions or direct calls to the patients to detect curable local recurrences. A matter of concern is the successive increase in postoperative breast ultrasonographic examinations.

In conclusion, postoperative follow-up breast ultrasonography showed occult malignancies clinically and mammographically in 1.2% of patients who had been treated previously for breast cancer. Surveillance ultrasonography, as an adjuvant to mammography, is helpful for the detection of an occult malignancy, clinically and mammographically, during the postoperative follow-up. Familiarity with the common location of the tumor recurrence is a prerequisite to an accurate ultrasonographic evaluation of these patients.

          © 2005 by the American Institute of Ultrasound in Medicine

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Breast MRI is usually utilized to inspect a lumpectomy site, Copyright Steven B. Halls, MD Last edited 28-November-2010

Following a lumpectomy, MRI has proven to be very helpful in assessing possible residual breast cancer in patients who have had a breast lump removed. With MRI, it is a little bit easier to determine whether the margins are negative or positive for breast very small amounts of breast carcinoma.

The mammogram image below, taken over 10 years after a lumpectomy was performed, shows an an apparent area of dense fibroglandular breast tissue and architectural distortion.
However, the contrast enhanced MRI image of the same breast, shown below, reveals an area of apparent tumor recurrence adjacent the scar tissue evident in the mammogram.

After lumpectomy and radiation treatement, a breast cancer tumor will enhance, while inactive scar tissue will not. For this reason, the 'confirmed negative' predictive value of MR for recurrence is more than 98%. Ultrasound is somewhat more limited in its ability to discriminate between scar and breast cancer tumor, but is still useful for guiding the biopsy process.