Sir,

We report a case of colon adenocarcinoma with choroidal metastasis. Intravitreal bevacizumab treatment was successful in one eye but failed in the other eye.

Case report

A 43-year-old man was diagnosed with colon adenocarcinoma in 2000. In 2008, bone metastasis was found and chemotherapy (oxaliplatin, fluorouracil, Calciumfolinat-Ebewe) was started. In April 2008, he complained of decreased vision OS. His vision was 20/20 OD and 20/400 OS. An elevated choroidal mass and exudative retinal detachment were seen in the temporal posterior pole extending beneath the macula OS (Figure 1a).

Figure 1
figure 1

(a) A large, elevated, orange choroidal mass in the temporal posterior pole extended beneath the macula to within 1 disc diameter of the optic nerve OS. Exudative retinal detachment was also found inferiorly. (b) Despite four intravitreal bevacizumab injections, the choroidal mass and massive exudative retinal detachment progressed OS. (c) Two small and orange choroidal masses were noted in the upper quadrant adjacent to the optic nerve OD. (d) After four intravitreal bevacizumab injections, the tumour masses had almost entirely regressed OD.

Full size image

Radiotherapy or intravitreal bevacizumab was offered. The patient chose the latter for convenience. Informed consent was obtained. Intravitreal 4-mg bevacizumab was injected. The mass enlarged despite four injections (Figure 1b). Vision deteriorated to hand motion.

Meanwhile, two small choroidal masses were seen in the upper quadrant adjacent to the optic nerve OD (Figure 1c). In May, intravitreal 4-mg bevacizumab was injected and marked shrinkage was appreciated (Figure 1d). In July, vision remained 20/20 even after four injections. The patient expired in August 2008. His family denied the request of autopsy.

Comment

Bevacizumab (Avastin, Genentech, Inc., South San Francisco, CA, USA) is a full-length recombinant humanized antibody against all isoforms of VEGF-A. We report the short-term results of intravitreal bevacizumab treatment on choroidal metastases of colon adenocarcinoma in a patient. In his first eye the tumour progressed, whereas in the second eye it regressed. There is no report on successful treatment of choroidal metastasis in one eye but failure in the other eye with intravitreal bevacizumab.

The mechanisms for the response are the antiangiogenic and antipermeability effects of bevacizumab on new tumour vessels and smaller lesions. The massive exudation that hinders bevacizumab from reaching the metastatic tumour may explain the non-response.

Manzano et al1 found bevacizumab not toxic to the retina at a concentration of 2.5 mg in rabbits. The safe dosage of intravitreal bevacizumab is presumed to be 7.5 mg in humans. Therefore, Amselem et al2 chose 4 mg bevacizumab for choroidal metastasis secondary to breast carcinoma. Kuo et al3 reported successful short-term regression treated with three monthly injections of 1.25 mg. In our case, 4 mg was used in consideration of the large choroidal tumour and exudative retinal detachment.

Intravitreal bevacizumab seems to be effective for early and small choroidal metastasis of colon adenocarcinoma. Further studies and longer follow-up are required to verify its efficacy.