Carcinoma cervix is the second most commonly occuring cancer in India. Brachytherapy forms the most important part radiation therapy Low dose rate Brachytherapy – Gold Standard Experience more than a century

1. Low Dose Rate Versus High Dose
Rate brachytherapy in Ca.Cervix

2. Introduction
• Carcinoma cervix is the second most
commonly occuring cancer in India.
• Brachytherapy forms the most important part
radiation therapy

3. • Low dose rate Brachytherapy – Gold
Standard
• Experience more than a century….

6. HDR for Ca. Cerix ??

8. Radiobiological advantages…..

9. Repair
The lower the dose rate of radiation a cell is exposed
to, the greater the likelihood of repair.
Late-reacting normal tissues seem more capable of
repair than tumor
The tumor is preferentially killed over normal tissue.

10. Reoxygenation
• Because of the duration of administration of
LDR, acute hypoxia corrects within the tumor
during treatment
• Oxygen enhancement ratio is lower for LDR
than for HDR.

11. Reassortment
During the overall treatment time of LDR,
tumor cells may pass from the relatively
radioresistant phases of late S and early G2
to the more radiosensitive phases of G2 and
M

12. Repopulation
The continuous administration of LDR
prevents repopulation during treatment.

13. Biological equivalent dose
• Calculated from LDR
• a/b ratio…
• Based on formulas !!!!

14. Toxicity
High dose / Fraction
Increased Late complications

15. HDR delivery
Total Dose?
Dose per fraction?
Conversion?
Schedule?

16. Orton et al, Metaanalysis

17. Optimisation???

19. URETHRA RECTUM

20. HDR for all cervix patients??

21. Small tumor & good
vaginal anatomy
Vaginal anatomy –
increase in
complications
Bulky central
disease with high
chance of central
recurrance

28. • Severely criticized
• Lacks any description of statistical methods,
• Were not randomized trials
• Many have never been published,
• None were referenced.
• Some of the LDR results used in the comparison are very poor, with
complication rates several times higher than those described by
Fletcher or Perez

29. What happens at longer follow up??

31. DSS

32. Pelvic recurrance free survival

35. • Teshima et al ; 1993
• 430 patients reported on 10-year OS
• 44% (114 out of 259) in the HDR arm versus
52.6% (90 out of 171) in the LDR arm

36. Other studies…

37. Other Factors…

38. • Patient’s expense…
• Source life…
• Need for intense QA…
• Setup up cost…

39. Important Msgs…
Radiobiology
Dose, Fraction & Schedule
Long term survival
Optimisation

40. Conclusion
• Carcinoma cervix – Life threatening disease
• For the price of convenience …, survival should never
be compromised
• LDR brachytherapy should be the standard of care in
carcinoma cervix until long term efficacy of HDR is
proven….