Metastasis resistant to therapy is the major cause of death from cancer. Despite almost 200 years of study, the process of tumor metastasis remains controversial. Stephen Paget initially identified the role of host-tumor interactions on the basis of a review of autopsy records. His "seed and soil" hypothesis was substantiated a century later with experimental studies, and numerous reports have confirmed these seminal observations. An improved understanding of the metastatic process and the attributes of the cells selected by this process is critical for the treatment of patients with systemic disease. In many patients, metastasis has occurred by the time of diagnosis, so metastasis prevention may not be relevant. Treating systemic disease and identifying patients with early disease should be our goal. Revitalized research in the past three decades has focused on new discoveries in the biology of metastasis. Even though our understanding of molecular events that regulate metastasis has improved, the contributions and timing of molecular lesion(s) involved in metastasis pathogenesis remain unclear. Review of the history of pioneering observations and discussion of current controversies should increase understanding of the complex and multifactorial interactions between the host and selected tumor cells that contribute to fatal metastasis and should lead to the design of successful therapy.

https://cancerres.aacrjournals.org/content/canres/early/2010/07/01/0008-5472.CAN-10-1040.full.pdf

AACR Centennial Series: The Biology of Cancer Metastasis: Historical Perspective

Cancer progression in humans is difficult to infer because we do not routinely sample patients at multiple stages of their disease. However, heterogeneous breast tumors provide a unique opportunity to study human tumor progression because they still contain evidence of early and intermediate subpopulations in the form of the phylogenetic relationships. We have developed a method we call Sector-Ploidy-Profiling (SPP) to study the clonal composition of breast tumors. SPP involves macro-dissecting tumors, flow-sorting genomic subpopulations by DNA content, and profiling genomes using comparative genomic hybridization (CGH). Breast carcinomas display two classes of genomic structural variation: (1) monogenomic and (2) polygenomic. Monogenomic tumors appear to contain a single major clonal subpopulation with a highly stable chromosome structure. Polygenomic tumors contain multiple clonal tumor subpopulations, which may occupy the same sectors, or separate anatomic locations. In polygenomic tumors, we show that heterogeneity can be ascribed to a few clonal subpopulations, rather than a series of gradual intermediates. By comparing multiple subpopulations from different anatomic locations, we have inferred pathways of cancer progression and the organization of tumor growth.

/pdf/inferring-tumor-progression-from-genomic-heterogeneity-1w9qtvzs3v.pdf

Inferring tumor progression from genomic heterogeneity

Intratumor heterogeneity represents a major obstacle to effective cancer treatment and personalized medicine. However, investigators are now elucidating intratumor heterogeneity at the single-cell level due to improvements in technologies. Better understanding of the composition of tumors, and monitoring changes in cell populations during disease progression and treatment, will improve cancer diagnosis and therapeutic design. Measurements of intratumor heterogeneity may also be used as biomarkers to predict the risk of progression and therapeutic resistance. We summarize important considerations related to intratumor heterogeneity during tumor evolution. We also discuss experimental approaches that are commonly used to infer intratumor heterogeneity and describe how these methodologies can be translated into clinical practice.

Cellular heterogeneity and molecular evolution in cancer.

With the emergence of individualized medicine and the increasing amount and complexity of available medical data, a growing need exists for the development of clinical decision-support systems based on prediction models of treatment outcome. In radiation oncology, these models combine both predictive and prognostic data factors from clinical, imaging, molecular and other sources to achieve the highest accuracy to predict tumour response and follow-up event rates. In this Review, we provide an overview of the factors that are correlated with outcome-including survival, recurrence patterns and toxicity-in radiation oncology and discuss the methodology behind the development of prediction models, which is a multistage process. Even after initial development and clinical introduction, a truly useful predictive model will be continuously re-evaluated on different patient datasets from different regions to ensure its population-specific strength. In the future, validated decision-support systems will be fully integrated in the clinic, with data and knowledge being shared in a standardized, instant and global manner.

/pdf/predicting-outcomes-in-radiation-oncology-multifactorial-3gfq2rvwlt.pdf

Predicting outcomes in radiation oncology--multifactorial decision support systems

Impact of 3D image-based PDR brachytherapy on outcome of patients treated for cervix carcinoma in France: results of the French STIC prospective study.

Purpose: To compare survival and severe late radiation toxicity between patients who received continuous low-dose-rate (LDR) brachytherapy (BT) and pulsed-dose-rate (PDR) BT for cervical cancer. Methods and Materials: A retrospective review of cervical cancer patients who underwent primary radiotherapy with or without concurrent cisplatin was performed. Late Grade 3 or worse toxicities were assessed using the National Cancer Institute Common Toxicity Criteria. The study endpoints were overall and disease-free survival and the probability of severe late toxicity. Results: A total of 109 patients (65.7%) received LDR BT and 57 (34.3%) received PDR BT. Seventy patients received concurrent chemotherapy with cisplatin. The 3-year overall survival and disease-free survival rate was 70% and 57% for the LDR group and 82% and 70% for the PDR group, respectively ( p = 0.25 and p = 0.19). The 3-year probability rate for late Grade 3 or worse toxicity was 7.4% for LDR BT patients and 7.6% for PDR BT patients, respectively ( p = 0.69) and 6.9% and 7.6%, respectively, for concurrent chemotherapy vs. none ( p = 0.69). Conclusion: No difference was found in severe late toxicity, overall survival, or disease-free survival between the LDR and PDR groups.

Comparison of late toxicity between continuous low-dose-rate and pulsed-dose-rate brachytherapy in cervical cancer patients

Purpose: To explore intratumor heterogeneity in gene expression profiles from patients with cervical cancer. Experimental Design: A total of 33 biopsies were obtained from 11 patients, sampling between two and five different areas for each tumor. The extracted RNA was hybridized onto the Affymetrix U133 Plus 2.0 oligonucleotide chip. The variance of expression within a patient ( W ), between patients ( B ) and the total variance ( T = W + B ) were calculated for each ProbeSet, and the ratio W/T was used as a measure of intratumor heterogeneity. Gene Ontology functional analysis was done to assess the function of genes that had high W/T (top 10%) and low W/T (bottom 10%) values. Results: In total, 448 ProbeSets (2.2% of the total) had W/T W/T > 0.90, indicating high intratumor heterogeneity. In total 14,473 ProbeSets (72.4%) had higher intertumor than intratumor heterogeneity ( W/T P P W/T > 0.5, more than six biopsies would be required to minimize the intratumoral heterogeneity to W/T is 0.3 to 0.4, four biopsies are required; and for low W/T of 0.16 to 0.3, only two to three biopsies would be needed. Conclusion: Although the intratumor heterogeneity was low for the majority of the tested ProbeSets, for many genes, multiple biopsies are required to obtain a reliable estimate of gene expression.

https://clincancerres.aacrjournals.org/content/clincanres/12/19/5632.full.pdf

Gene Expression Profiling in Cervical Cancer: An Exploration of Intratumor Heterogeneity

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Comparison of late toxicity between continuous low-dose-rate and pulsed-dose-rate brachytherapy in cervical cancer patients

Gene Expression Profiling in Cervical Cancer: An Exploration of Intratumor Heterogeneity