Confirmation of double-peaked time distribution of mortality among Asian breast cancer patients in a population-based study.

Division of Clinical Trials and Epidemiological Sciences, National Cancer Centre, Singapore.
Breast cancer research: BCR (Impact Factor: 5.87). 02/2007; 9(2):R21. DOI: 10.1186/bcr1658
Source: PubMed

ABSTRACT Double-peaked time distributions of the mortality hazard function have been reported for breast cancer patients from Western populations treated with mastectomy alone. These are thought to reflect accelerated tumour growth at micrometastatic sites mediated by angiogenesis after primary tumour removal as well as tumor dormancy. Similar data are not available for Asian populations. We sought to investigate whether differences exist in the pattern of mortality hazard function between Western breast cancer patients and their Asian counterparts in Singapore, which may suggest underlying differences in tumor biology between the two populations.
We performed a retrospective cohort study of female unilateral breast cancer patients diagnosed in Singapore between October 1994 and June 1999. Data regarding patient demographics, tumour characteristics and death were available. Overall survival curves were calculated using the Kaplan-Meier method. The hazard rate was calculated as the conditional probability of dying in a time interval, given that the patient was alive at the beginning of the interval. The life table method was used to calculate the yearly hazard rates.
In the 2,105 women identified, 956 patients (45.4%) had mastectomy alone. Demographic characteristics were as follows: 86.5% were Chinese, 45.2% were postmenopausal, 38.9% were hormone receptor positive, 54.6% were node negative and 44.1% had high histological grade. We observed a double-peaked mortality hazard pattern, with a first peak in mortality achieving its maximum between years 2 and 4 after mastectomy, and a second large peak in mortality during year 9. Analyses by subgroups revealed a similar pattern regardless of T stage, or node or menopausal status. This pattern was also noted in high-grade tumors but not in those that were well to moderately differentiated. The double-peaked pattern observed in Singaporean women was quantitatively and qualitatively similar to those reported in Western series.
Our study confirms the existence of a double-peaked process in Asian patients, and it gives further support to the tumour dormancy hypothesis after mastectomy.

  • [Show abstract] [Hide abstract]
    ABSTRACT: The dynamics of disease recurrence shows a bimodal pattern with a fairly broad dominant peak at about 1.5-2 years after surgery followed by a second peak at about 5 years. Nowadays, this clinical pattern is explained by assuming that primary breast tumours as well as their metastases have phases of both arrested (tumour dormancy) and active Gompertzian growth. Tumour dormancy at metastatic sites is currently ascribed to biological particularities of local tissue microenvironments that inhibit the growth of tumour cells. However, in some patients, tumour dormancy appears to also depend on the direct interplay between the primary tumour and those metastases, a biological phenomenon called "concomitant resistance". Concomitant resistance is related to three biological processes: concomitant immunity, tumour-induced angiogenesis and athrepsia. Concomitant resistance can explain the bimodal relapse pattern of breast cancer patients as well as many other clinical phenomena such as the better clinical outcome among patients surgically treated during the putative early luteal phase, or the worse clinical outcome of African-American premenopausal women. Any therapeutic interventions (even surgery) can affect concomitant resistance with the potential to induce a worse as well as a better clinical outcome. This should be taken into account when planning new treatment strategies.
    CANCER AND METASTASIS REVIEW 12/2013; · 9.35 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The aim of this study was to evaluate the effect of surgery on the kinetics of CTCs in breast cancer patients. The detection of CK-19 mRNA-positive CTCs in the blood by RT-PCR was analysed in 104 stage 0-IIIA patients at 4 time-points: prior to surgery, upon completion, 24 h after surgery and 15 days after surgery. Furthermore, a late sample was assessed prior to initiation of adjuvant chemotherapy in a subgroup of 53 patients. As negative controls, peripheral blood was obtained from 50 female patients undergoing excision of benign breast lesions and from 11 female patients receiving surgery for early-stage colorectal cancer. A significant percentage of blood samples from breast cancer patients (14.4%) were negative for CK-19 preoperatively but turned transiently positive early postoperatively. However, no significant difference in CK-19 mRNA detection was noted among the first 4 examined time-points. There was no significant correlation between CK-19 mRNA-positive cells and classic prognostic factors. A significant increase in CK-19 mRNA-positivity (32.1%) was observed in a late sample of the subgroup of 53 patients before adjuvant chemotherapy after a median of 54 days, postoperatively. Surgery may result in CTC detection in a small proportion of early breast cancer patients. There is no clear correlation to indicate which patients are expected to have detectable CTCs. Although CTCs are detected in a small proportion of patients during the perioperative period, the detection rate may increase over time and with longer follow-up.
    European journal of surgical oncology: the journal of the European Society of Surgical Oncology and the British Association of Surgical Oncology 03/2011; 37(5):404-10. · 2.56 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: According to the concept of tumor dormancy, tumor cells may exist as single cells or microscopic clusters of cells that are clinically undetectable, but remain viable and have the potential for malignant outgrowth. At metastatic sites, escape from tumor dormancy under more favorable local microenvironmental conditions or through other, yet undefined stimuli, may account for distant recurrence after supposed "cure" following surgical treatment of the primary tumor. The vast majority of evidence to date in support of the concept of tumor dormancy originates from animal studies; however, extensive epidemiologic data from breast cancer strongly suggests that this process does occur in human disease. In this review, we aim to demonstrate that metastatic tumor dormancy does exist in cutaneous melanoma based on evidence from mouse models and clinical observations of late recurrence and occult transmission by organ transplantation. Experimental data underscores the critical role of impaired angiogenesis and immune regulation as major mechanisms for maintenance of tumor dormancy. Finally, we examine evidence for the role of surgery in promoting escape from tumor dormancy at metastatic sites in cutaneous melanoma.
    Cancers. 01/2011; 3(1):730-46.

Full-text (2 Sources)

Available from