Tumor cells in venous blood draining mammary carcinomas

Metastatic dormancy imposed by the primary tumor: does it exist in humans?

BACKGROUND

In cancer patients, occult micrometastases may become apparent shortly after removal of the primary tumor. Animal experiments have shown that metastatic dormancy is maintained by apoptosis, and that primary tumor removal induces a flare-up of angiogenesis, leading to metastatic outgrowth. This phenomenon has led to the hypothesis that the primary tumor generates certain factors that inhibit angiogenesis at distant sites. It is still unknown whether such a phenomenon is operative in human cancer as well. Should it occur, it might have important therapeutic consequences.

MATERIALS AND METHODS

Evidence for such a mechanism may be obtained from studies that analyze a series of tissue samples of metastases, taken before or after surgical removal of the primary lesion.

RESULTS

Data from our laboratory on colorectal cancer have shown that, in the absence of the primary tumor, vascular density in the metastases is increased as well as their metabolic activity, as measured by (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET). Mitotic activity is increased mildly, while levels of apoptosis are collapsed.

CONCLUSION

These data indicate that a mechanism of primary-tumor-induced inhibition of angiogenesis exists, maintaining metastatic dormancy. We now suggest that this mechanism may be exploited to avoid the use of exogenous, potentially harmful angiogenesis inhibitors such as bevacizumab in a neoadjuvant setting. Treatment of patients with the primary tumor still in situ could thus be restricted to chemotherapy, since the synergistic effect of an angiogenesis inhibitor would be generated by the primary tumor itself. In the present paper the clinical relevance and possible consequences of our findings and suggestions are discussed.

Cutaneous melanoma: therapeutic lymph node and elective lymph node dissections, lymphatic mapping, and sentinel lymph node biopsy

Early clinical observation in cancer patients suggested that tumors spread in a methodical, stepwise fashion from the primary site, to the regional lymphatics, and only then to distant locations. Based on these observations, the regional lymphatics were believed to be mechanical barriers, at least temporarily preventing the widespread dissemination of tumor. Despite evidence now available disputing its validity, this barrier theory has guided the surgical management of the regional lymphatics in cancer patients for more than a century, influencing the use of such surgical modalities as therapeutic lymph node dissection, elective lymph node dissection, and most recently lymphatic mapping and sentinel lymph node biopsy. No published randomized controlled trial exists that demonstrates improved overall patient survival for cancer of any type, including melanoma, after surgical excision of regional lymphatics. This article will review the biology of lymphatics as it relates to regional tumor metastasis, and based on available information, offer practical recommendations for the clinical dermatologist and their patients who have cutaneous melanoma.

The management of regional lymph nodes in cancer

Early clinical observation in cancer patients suggested that tumours spread in a methodical, stepwise fashion from the primary site to the regional lymphatics, and only then to distant locations. Based on these observations, the regional lymphatics were believed to be mechanical barriers preventing the widespread dissemination of tumour. Despite evidence now available disputing its validity, this barrier theory has guided the surgical management of the regional lymphatics for more than a century, influencing the use of such surgical modalities as therapeutic lymph node dissection, elective lymph node dissection and most recently sentinel lymph node biopsy. No published randomized controlled trial exists that demonstrates improved overall survival for patients with cancer of any type undergoing surgery of the regional lymphatics. We believe the presence of tumour in the regional lymphatics indicates the presence of systemic disease, and therapeutic interventions should be directed accordingly.

Molecular biology of breast cancer metastasis. Clinical implications of experimental studies on metastatic inefficiency

Recent technological advances have led to an increasing ability to detect isolated tumour cells and groups of tumour cells in patients' blood, lymph nodes or bone marrow. However, the clinical significance of these cells is unclear. Should they be considered as evidence of metastasis, necessitating aggressive treatment, or are they in some cases unrelated to clinical outcome? Quantitative experimental studies on the basic biology of metastatic inefficiency are providing clues that may help in understanding the significance of these cells. This understanding will be of use in guiding clinical studies to assess the significance of isolated tumour cells and micrometastases in cancer patients.

Inhibition of metastases by anticoagulants

Metastasis involves several distinct steps, including one in which the tumor cell, after entry into the bloodstream, comes to rest in a capillary located at the distant site where a metastatic tumor will ultimately form. Components of the blood-clotting pathway may contribute to metastasis by trapping cells in capillaries or by facilitating adherence of cells to capillary walls. Conceivably, anticoagulants could interfere with this step in the metastatic process. In this review, we have summarized current knowledge on the interaction of malignant cells, clotting factors, and anticoagulants. We used computerized (MEDLINE) and manual searches to identify studies done in humans, in animals, and in in vitro systems that were published in English between 1952 and 1998. We found many reports that the formation of metastatic tumors could be inhibited by heparin, a vitamin K antagonist (warfarin), and inhibitors of platelet aggregation (prostacyclin and dipyridamole). Despite these encouraging preliminary results and a compelling biochemical rationale, only limited information exists on the clinical use of anticoagulants for the prevention or treatment of metastatic cancer because there have been so few controlled and prospectively randomized studies on this topic. In view of the preliminary results, anticoagulants may hold promise for the prevention and treatment of metastases. We believe that larger controlled investigations are strongly warranted to evaluate the clinical potential of anticoagulants for the prevention and treatment of metastases in humans.

Effect of retained components of excised tumor upon coexisting tumor

Effects of locally treated and retained tumor tissue on the growth of a tumor at another site were investigated using Lewis rats bearing syngeneic fibrosarcoma. When an established tumor had completely regressed upon repeated intratumoral injections of L-phenylalanine mustard (PhM), the growth of secondarily transplanted tumor cells was inhibited. However, early excision of the PhM-injected tumor prevented the development of this effect. To study this effect directly, we excised one of the two established tumors in each thigh, and reinoculated into the excision wound either freeze-lysed 1 X 10(8) tumor cells (TC) or lysate chemically modified with PhM (PTC). We found that TC inoculation into the excision wound in 7 rats inhibited the growth of the remaining tumor and extended survival time (mean +/- SE, 27 +/- 1 days). With inoculation of PTC into the excision wound, the remaining tumor regressed and survival was significantly prolonged (32 +/- 2 days). In contrast, 7 untreated rats, each bearing two tumors, had a mean survival time of 22 +/- 0.1 days. Excision of one tumor (6 rats) did not affect the growth of the remaining tumor or survival time (23 +/- 1 days). We employed PhM to modify the immunogenicity of TC. However, if PhM dissociates from PTC, its cytotoxic effect may directly inhibit growth of the distant tumor. To examine this possibility, we divided 30 rats who had excision of one tumor, into three groups of 10 10.(ABSTRACT TRUNCATED AT 250 WORDS)

Prognostic significance of peritumoral vessel invasion in clinical trials of adjuvant therapy for breast cancer with axillary lymph node metastasis

To assess the prognostic significance of peritumoral vessel invasion, data were examined for 1,510 women entered into the Ludwig Breast Cancer Group Trials I to IV evaluating adjuvant therapy for operable breast cancer with axillary nodal metastasis. Vessel invasion by tumor cells was identified by routine light microscopy in 59 per cent (889 of 1,510) of the patients and was equally distributed between premenopausal/perimenopausal (60 per cent, 468 of 778) and postmenopausal (58 per cent, 421 of 732) women. In logrank analyses stratified by nodal status (one to three or four or more positive nodes), the four-year disease-free survival (DFS) rate was significantly lower in patients with vessel invasion than in women without vessel invasion (50 per cent versus 65 per cent, P less than 0.0001). This DFS difference was seen for both premenopausal/perimenopausal (P = 0.0004) and postmenopausal (P = 0.0002) patients. The four-year overall survival rate was also lower in patients with vessel invasion (71 per cent versus 82 per cent, P = 0.0006), both for premenopausal/perimenopausal (P = 0.002) and postmenopausal (P = 0.04) women. The presence of vessel invasion was significantly associated with increasing numbers of positive axillary lymph nodes, rising tumor grade, nonstellate tumor border growth pattern, and higher steroid hormone receptor content of the primary tumor. The assessment of peritumoral vessel invasion continued to have prognostic significance for DFS (P less than 0.0001) and overall survival (P = 0.003) when evaluated in multivariate models controlling for treatment assigned, nodal status, tumor size, estrogen receptor status, menopausal status, and age. Depending on the subpopulation, patients with vessel invasion had a 41 per cent to 54 per cent greater risk of treatment failure than those without vessel invasion and a 29 per cent to 64 per cent greater risk of death. The percentage of treatment failures at distant sites was higher for women with than for those without vessel invasion (27 per cent versus 18 per cent, P = 0.003). In patients with axillary lymph node metastases, peritumoral vessel invasion may be a sign of increased systemic disease burden.

The impact of pathology on the biologic, diagnostic, prognostic, and therapeutic considerations in breast cancer

It has become readily appreciated that an understanding of the pathologic aspects of breast cancer is essential to the planning of many clinical trials. The clinical findings obtained from such studies unquestionably served as a stimulus for other relevant pathologic investigations but did not always resolve all of the long-standing pathologic problems associated with the diagnosis of breast diseases. This article addresses some of the pathologic problems that have a bearing on the biologic, diagnostic, prognostic, and therapeutic aspects of breast cancer.

Pathologic findings from the National Surgical Adjuvant Project for Breast Cancers (protocol no. 4). X. Discriminants for tenth year treatment failure

A search for prognostic discriminants of treatment failure in the tenth postmastectomy year was undertaken in 614 patients enrolled in protocol no. 4 of the National Surgical Adjuvant Project for Breast Cancers treated by radical mastectomy. Exploratory analyses of 38 pathologic and 6 clinical features disclosed 16 and 13 variables significantly related to nodal status and treatment failure, respectively. However, multivariate analyses with life tables adjusted or controlled for nodal status revealed that patients whose tumors measured less than 2 cm had a more favorable clinical course. All of the characteristics were also explored when patients were stratified according to numbers of nodal metastases, the most significant prognostic discriminant for disease-free survival in the tenth year. A germinal center predominance lymph node pattern and high histologic grade according to our conventional grading method were observed to adversely influence disease-free survival in patients with negative nodes. A strong trend in this manner was also observed with tumors greater than or equal to 2 cm and types 3 and 5 scar cancers. Histologic grade and tumor size were significantly recognized as discriminatory in patients with 4+ nodes but no factors were significantly observed in the group of patients with 1 to 3 positive nodes. A possible explanation for this inconsistency is discussed. For the most part, these factors were also encountered by us previously at the 5-year postoperative period. Only the presence of 13+ nodal metastases and types 3 and 5 scar cancers and cancers without scar appeared to discriminate success or failure between the fifth and tenth year. It is therefore concluded that nodal category, germinal center predominance, histologic grade, and tumor size, in the contexts noted, represent strong prognostic discriminants exerting a rather constant influence on disease-free survival at least to the tenth postmastectomy period. The prognostic value of categorizing those patients with 4+ positive nodes into subgroups with 4 to 6, 7 to 12 and 13+ is reaffirmed. The actual disease-free survival of patients in the tenth year was not strikingly different from that observed previously by us at 5 years in this cohort.

Cancer metastasis: a product of tumor-host interactions

Metastasis continues to be the most devastating event for the patient with an established primary cancer. The most significant therapeutic problems are: (1) treatment of patients with established macrometastases, (2) identification of patients who have micrometastases and (3) the development of adequate adjunctive therapies for micrometastases. It is hoped that our evolving understanding of the biology of experimental metastasis and the high level of premium quality laboratory research ongoing in this area will result in further resolution of this clinical problem or, at least, a better understanding of this most extreme expression of the malignant phenotype.