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• Re: Thermochemotherapy in hereditary retinoblastoma
  Santosh G Honavar, MD
  Published on: 21 May 2003

• Published on: 21 May 2003

  Re: Thermochemotherapy in hereditary retinoblastoma

  • Santosh G Honavar, MD
  • Other Contributors:
    • Ramesh Murthy, FRCS; Milind Naik, MD; Vijay Anand P. Reddy, MD

  Dear Editor

  Schueler and associates describe their experience with thermochemotherapy (TCT) in bilateral retinoblastoma.[1] The reported results of transpupillary thermotherapy used in combination with chemotherapy are encouraging, with 86-96% tumor control.[2,3] In the current series, however, local recurrence occurred in 38%.

  The dosage of carboplatin used in the current series was 10 mg/Kg BW, which is lower...

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  Dear Editor

  Schueler and associates describe their experience with thermochemotherapy (TCT) in bilateral retinoblastoma.[1] The reported results of transpupillary thermotherapy used in combination with chemotherapy are encouraging, with 86-96% tumor control.[2,3] In the current series, however, local recurrence occurred in 38%.

  The dosage of carboplatin used in the current series was 10 mg/Kg BW, which is lower than the standard dosage of 18.6-mg/Kg BW.[4] Lower dose of carboplatin, the key drug in the chemotherapy regimen for retinoblastoma, could have influenced the higher recurrence rate.

  The authors mention that they treated submacular tumors with TCT. However, in our experience, tumors located in the macular area are better treated initially with chemotherapy for 3-6 cycles in order to achieve maximum possible reduction in tumor size before considering thermotherapy. Chemo reduced macular tumors tend to shrink away from the fovea towards one of the major arcades or the optic nerve, thus exposing the foveal region. Residual tumor beyond 3-6 cycles of chemotherapy could be treated with thermotherapy. A smaller scar thus produced may optimize residual central vision.

  The high mean total duration of thermotherapy in the current series is probably because of a smaller spot size of 0.4 mm. The diode laser (Iris Medical Inc, Mountain View, Ca, USA) with an operating microscope adapter allows for a spot size of 0.8,1.2,and 2.0 mm.[3] The relatively newer large spot indirect ophthalmoscope delivery system provides a 1.2mm spot size.[3] A larger spot size will indeed reduce the duration of thermotherapy and allow for a more uniform coverage. Corneal, iris and lens complications are minimized with better convergent beam optical systems currently available.

  We believe that with higher dose of carboplatin, staggered thermotherapy for submacular tumors, use of better optical systems for delivery and a larger spot size for thermotherapy, and judicious selection of cases, the tumor regression and vision salvage with TCT could be further optimized.

  References

  (1) Schueler AO, Jurklies C, Heimann H et al. Thermochemotherapy in hereditary retinoblastoma. Br J Ophthalmol 2003; 87:90-95.

  (2) Lumbraso L, Doz F, Urbeita M et al. Chemothermotherapy in the management of retinoblastoma. Ophthalmology 2002; 109:1130-1136

  (3) Shields CL, Santos CM, Diniz W et al. Thermotherapy for retinoblastoma. Arch Ophthalmol 1999; 117:885-893.

  (4) Shields CL, Honavar SG, Shields JA et al. Factors predictive of recurrence of retinal tumors, vitreous seeds, and subretinal seeds following chemoreduction for retinoblastoma. Arch Ophthalmol 2002; 120:460-464.

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  Conflict of Interest:
  None declared.

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