Devita, Hellman, and Rosenberg's Cancer

LWBK1006-15 LWW-Govindan-Review December 7, 2011 19:5

180 DeVita, Hellman, and Rosenberg’s CANCER: Principles and Practice of Oncology Review

and to guide intervention. It is faster and cheaper than breast MRI. The

role of MRI of the breast is currently under study. Until recently, the role

of MRI in screening has been limited because of the inability to biopsy

lesions that were not palpable and only seen on MRI. MRI-compatible

biopsy devices have recently been developed. Studies are under way to

determine the makeup of these mammographically occult, sonographi-

cally occult, and nonpalpable lesions.

Answer 15.31. The answer is A.

Understanding breast cancer staging and potential therapy requires one to

realize that more than one focus of breast cancer in one quadrant (multi-

focal disease) may warrant a wider excision and that disease in more than

one quadrant (multicentric disease) may warrant mastectomy. Sonogra-

phy is useful in depicting axillary adenopathy, which also affects staging,

but sonography is limited in depicting carcinoma in situ. MRI is sensitive

in evaluating ipsilateral and contralateral breasts in women with can-

cer. It is particularly useful in depicting invasive lobular carcinoma and

finding an occult primary tumor in patients presenting with axillary lym-

phadenopathy. Nuclear medicine techniques may also be used for breast

cancer staging. PET may play a role in depicting metastases and showing

tumor response to therapy. Lymphoscintigraphy also has become useful

for lesions less than 5 cm and in some centers is considered the standard

of care. For larger lesions, the results of lymphoscintigraphy may not be

reliable for sentinel node mapping.

Answer 15.32. The answer is E.

As useful as breast MRI may be on a case-by-case basis, its impact on

breast cancer mortality has yet to be determined. MRI is a sensitive tech-

nique that is not as specific; consequently, biopsy of detected lesions may

be needed. For this reason, MRI-compatible biopsy instruments have

been devised. MRI is still expensive and requires intravenous contrast

for dynamic enhancement. In the postoperative breast, however, MRI

can be useful in separating recurrent tumor from postoperative change.

Answer 15.33. The answer is E.

Colorectal cancer is the most common gastrointestinal malignancy. As a

result, many studies have been performed to determine an effective way

of screening for this malignancy. MDCT has recently allowed for the

propagation of CT colography, which shows early promise. This tech-

nique is relatively noninvasive and does not require intravenous contrast.

In the initial staging of colorectal cancer, CT, MRI, and TRUS are all

commonly used. TRUS allows for clear visualization of the layers of the

bowel wall and can allow for accurate depiction of tumor penetration.

TRUS does not allow for visualization of the entire colon. CT is best used

for assessing metastases and lymphadenopathy. Even MDCT does not

allow for differentiation of the layers of the bowel wall. MRI, because

of its better soft-tissue resolution, is superior to CT for localized staging.

High-resolution sequences may allow for clearer depiction of extension