Alternating sequential endocrine therapy: tamoxifen and medroxyprogesterone acetate versus tamoxifen in postmenopausal advanced breast cancer patients

Adjuvant cyclic Tamoxifen and Megestrol acetate treatment in postmenopausal breast cancer patients – Longterm follow-up

AIMS

To evaluate possible differences in effect on recurrence-free survival (RFS) and overall survival (OS) in node positive postmenopausal breast cancer patients receiving Tamoxifen or cyclic Tam and Megestrol acetate as adjuvant treatment.

METHODS

Between 1989 and 1994, 489 patients with pT(1-2)pN+ hormone receptor positive or unknown tumours were included in a randomized national multicenter study to receive either Tam alone or cyclic Tam (8 weeks) and MA (8 weeks) for 2 years. Final follow-up was completed as of June 2002. Time from start of treatment to first recurrence and novel primary breast tumour, overall survival and cancer specific survival were estimated.

RESULTS

No differences in RFS, OS or cancer specific survival were observed between the two treatment groups.

CONCLUSIONS

Adjuvant treatment used as standard Tam alone, compared to Tam and MA, as employed in this group of patients gave similar outcomes. Side effects that led to cessation of study medication were observed in both arms.

Continuous versus intermittent tamoxifen versus intermittent/alternated tamoxifen and medroxyprogesterone acetate as first line endocrine treatment in advanced breast cancer: an EORTC phase III study (10863)

BACKGROUND

Continuous ligand depletion of endocrine responsive tumours may enhance resistance to therapy. Intermittent treatment with tamoxifen (T) was considered to mimic (incomplete) ligand depletion and reintroduction. Furthermore it was postulated that alternating tamoxifen with a non-cross resistant endocrine modality could (further) postpone hormone resistance.

PATIENTS AND METHODS

Postmenopausal patients with advanced breast cancer who did not progress after 4 months of first line T therapy were randomised to continue T (40 mg daily) or to 2 monthly intermittent T or intermittent/alternated T and medroxyprogesterone acetate (MPA, 300 mg daily). At progression during break or during MPA, T should be reintroduced. Endpoints of the study were progression free survival (PFS), time to resistance to tamoxifen and overall survival (OS).

RESULTS

Of 593 registered patients, 276 were randomised. After 8 years follow-up the median PFS for continuous T, intermittent T and intermittent/alternated T and MPA was 11.0 (8.1-15.2), 8.0 (6.2-12.4) and 10.8 (7.1-16.7) months, respectively (NS). Resistance to tamoxifen was established only in 84%, 70% and 55% of patients in the three treatment arms, respectively. The median times from randomisation to resistance to tamoxifen were 12.5 (9.1-21.1), 13.2 (8.8-19.8) and 24.0 (16.9-60.9) months, respectively (p<0.001), without translation in differences in survival times.

CONCLUSION

Intermittent T or intermittent/alternated T and MPA had no impact on PFS or OS as compared with classical continuous T in patients with advanced breast cancer. Intermittent/alternated T and MPA resulted in prolonged time to resistance to T, but this might partly be due to bias by omittance of the proof of tamoxifen resistance in a high proportion of the patients in this treatment arm.

Systematic reviews of chemotherapy and endocrine therapy in metastatic breast cancer

Metastatic breast cancer is incurable but often responsive to treatment. There is little evidence-based consenus on when to use which treatments, in what combination and for how long. Systematic reviews were performed on 12 prospectively defined, clinically relevant research questions to support the development of evidence-based clinical practice guidelines. A comprehensive search of Medline from 1966 to 1996 identified over 1800 controlled trials. Eligibility and data extraction were performed independently by two blinded reviewers. Trial results were summarised by ratios of median survivals (RMS) and P -values for survival curve comparisons with meta-analysis by weighted combination of these statistics. Sixty-five publications reporting 97 treatment comparisons were included. There was moderate evidence that more rather than fewer cycles of chemotherapy improved survival (RMS:1.23, P -0.01). The evidence did not support: higher rather than lower doses of chemotherapy (or of endocrine therapy); any one class of endocrine agent over all others; multiple endocrine agents over a single agent; or, combined chemotherapy and endocrine therapy over either single modality. Only six trials assessed quality of life revealing better quality of life with more rather than fewer cycles of chemotherapy and with standard rather than lower doses of chemotherapy. These systematic reviews reveal counterintuitive evidence useful to everyday practice, in particular that more rather than fewer cycles of chemotherapy lead to better quality of life and longer survival.