In the large majority of patients with breast cancer, lymphoscintigraphy and gamma-probe-guided surgery can be used to locate the sentinel node in the axilla, and thereby provide important information about the status of axillary nodes. Patients without clinical involvement of the axilla should undergo sentinel-node biopsy routinely, and may be spared complete axillary dissection when the sentinel node is disease-free.
Sentinel lymph node biopsy using a gamma ray-detecting probe allows staging of the axilla with high accuracy in patients with primary breast cancer. A randomized trial is necessary to determine whether axillary dissection may be avoided in those patients with an uninvolved sentinel lymph node.
Radioembolization (RE) of liver cancer with 90Y-microspheres has been applied in the last two decades with notable responses and acceptable toxicity. Two types of microspheres are available, glass and resin, the main difference being the activity/sphere. Generally, administered activities are established by empirical methods and differ for the two types. Treatment planning based on dosimetry is a prerogative of few centers, but has notably gained interest, with evidence of predictive power of dosimetry on toxicity, lesion response, and overall survival (OS). Radiobiological correlations between absorbed doses and toxicity to organs at risk, and tumor response, have been obtained in many clinical studies. Dosimetry methods have evolved from the macroscopic approach at the organ level to voxel analysis, providing absorbed dose spatial distributions and dose–volume histograms (DVH). The well-known effects of the external beam radiation therapy (EBRT), such as the volume effect, underlying disease influence, cumulative damage in parallel organs, and different tolerability of re-treatment, have been observed also in RE, identifying in EBRT a foremost reference to compare with. The radiobiological models – normal tissue complication probability and tumor control probability – and/or the style (DVH concepts) used in EBRT are introduced in RE. Moreover, attention has been paid to the intrinsic different activity distribution of resin and glass spheres at the microscopic scale, with dosimetric and radiobiological consequences. Dedicated studies and mathematical models have developed this issue and explain some clinical evidences, e.g., the shift of dose to higher toxicity thresholds using glass as compared to resin spheres. This paper offers a comprehensive review of the literature incident to dosimetry and radiobiological issues in RE, with the aim to summarize the results and to identify the most useful methods and information that should accompany future studies.
Background. Axillary lymph‐node dissection is an important staging procedure in the surgical treatment of breast cancer. However, early diagnosis has led to increasing numbers of dissections in which axillary nodes are free of disease. This raises first, questions about the need for the procedure. We carried out a study to assess, first, whether a single axillary lymph node (sentinel node) initially receives malignant cells from a breast carcinoma and, second, whether a clear sentinel node reliably forecasts a disease‐free axilla.
Methods. In a consecutive series of 163 women with operable breast carcinoma, we injected microcolloidal particles of human serum albumin labelled with technetium‐99m. This tracer was injected subdermally, close to the tumor site, on the day before surgery, and scintigraphic images of the axilla and breast were taken 10 min, 30 min, and 3 h later. A mark was placed on the skin over the site of the radioactive node (sentinel node). During breast surgery, a hand‐held γ‐ray det$ector probe was used to locate the sentinel node, and make possible its separate removal via a small axillary incision. Complete axillary lymphadenectomy was then done. The sentinel node was tagged separately from other nodes. Permanent sections of all removed nodes were prepared for pathological examination.
Findings. From the sentinel node, we could accurately predict axillary lymph‐node status in 156 (97.5%) of the 160 patients in whom a sentinel node was identified, and in all cases (45 patients) with tumours less than 1.5 cm in diameter. In 32 (38%) of the 85 cases with metastatic axillary nodes, the only positive node was the sentinel node.
Interpretation. In the large majority of patients with breast cancer, lymphoscintigraphy and γ‐probe‐guided surgery can be used to locate the sentinel node in the axilla, and thereby provide important information about the status of axillary nodes. Patients without clinical involvement of the axilla should undergo sentinel‐node biopsy routinely, and may be spared complete axillary dissection when the sentinel node is disease‐free.
Preservation of healthy lymph nodes may have beneficial consequences. Axillary dissection should not be performed in breast cancer patients without first examining the sentinel node.
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