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Centre for Evidence-
Based Medicine

Example NNTs - Oncology

Condition or Disorder Intervention vs. Control Outcome Follow-up Duration Event Rates % NNT (95% CI)
CER EER
Breast cancer1; Postmenopausal women with breast cancer Radiotherapy plus tamoxifen vs. tamoxifen alone Recurrence (both locoregional recurrence and distant metastasis) 10 years 60 47 8 (6 to 13)
Stages II and III breast cancer2 Adjuvant chemotherapy + radiotherapy vs. chemotherapy alone Locoregional recurrence 10 years 26 5 5 (4 to 6)
Locally advanced prostate cancer3 Radiotherapy + goserelin vs. radiotherapy alone Death 5 years 28 17 10 (5 to 34)
Acute myeloid leukemia; autologous bone-marrow transplantation after intensive chemotherapy4 Bone-marrow transplantation vs. no further treatment Relapse 7 years 53 34 5 (3 to 11)
Relapse or cancer-specific death 57 45 9 (5 to 80)
Death 49 40 Not significant
Breast cancer; preservation of the intercostobrachial nerve during axillary node clearance5 Preservation vs. sacrifice of the intecostobrachial nerve Some sensory deficit 3 months 84 63 5 (3 to 24)
Breast cancer6 Radiotherapy plus tamoxifen vs. tamoxifen alone All recurrences 10 years 60 47 8 (6 to 13)
Locoregional recurrence with or without distant metastases 35 8 4 (4 to 5)
Node-positive prostate cancer7 Antiandrogen therapy immediately after surgery vs. observation Death 7.1 years 35 15 5 (3 to 34)
Death from prostate cancer 31 6.4 4 (3 to 10)
Any recurrence 82 15 2 (2 to 2)
Prostate cancer8 Pelvic floor re-education program (included education about the anatomy and function of the bladder and pelvic floor, active pelvic-floor muscle exercises and biofeedback) vs. placebo program (information about the origin of their incontinence and placebo electrotherapy applied to the abdomen and thighs, but that could not affect pelvic floor function) Incontinence rate at 3 months (continence was defined as a loss of ≤ 2g of urine on both the 24-hour and 1-hour pad test 1 year 44 10 3 (2 to 6)
Incontinence at 1 year 17 4 8 (4 to 72)

References

  1. Lancet 1999; 353:1641-8
  2. N Engl J Med 1997 Oct 2;337(14):949-55
  3. N Engl J Med 1997 Jul 31;337(5):295-300
  4. Lancet 1998 Mar 7;351(9104):700-8
  5. Br J Surg 1998 Oct;85(10):1443-5
  6. Lancet 1999 May 15;353(9165):1641-8
  7. N Engl J Med. Dec 9, 1999; 341: 1781-8
  8. Lancet. Jan 8 2000; 355: 98-102