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Prophylactic Cranial Radiation: LS-SCLC Review


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My layman's review of recent literature (3 yrs) poses several interesting topics and questions for oncologists and radiologist as it relates to Prophylactic Cranial Irradiation (PCI) in limited-stage, small cell lung cancer (LS-SCLC). Currently, PCI is standard treatment after standard first-line chemoradiation therapy (CRT) when the cancer partially or completely responds.

Chemo does not cross the blood brain barrier effectively and brain metastasis (BM) may occur during first-line treatment. The literature suggests that an MRI evaluation of the brain just prior to PCI , to determine number and location of BM, if any, is extremely important. The literature suggests that the time from start of CRT to start of PCI is critical. Data indicates that 4 months, CRT to PCI, tends to have BM show up and longer intervals have even more showing up. Typical CRT treatment consists of 4 to 6 cycles every 21 days with radiotherapy ending near the 4th cycle. This translates to 3 months (86 days) and 4 months (128 days), respectively. Any prolonged changes in the treatment schedule risks BM. There is some suggestion that PCI be given prior to the end of CRT but additional symptoms might discourage this.

One of the symptoms of PCI is memory issues. It is becoming common and NCCN guidelines recommend the drug memantine during and after PCI to counteract or slow down memory issues. The literature indicates that the hippocampus is associated with memory and clinical trials are studying how common BM occur in the hippocampus. The literature seems to suggest that the risk of BM in the hippocampus is low. Additionally, there are clinical trials for irradiating all but the hippocampus in the brain. The term used is hippocampus-avoidance PCI (HA- PCI) or HA whole brain radiation therapy ( HA-WBRT). The newest term that I found is left-hippocampus-avoidance PCI or WBRT (LHA-PCI, LHA-WBRT). I didn't spend much time on this one but I guess the left side is more important. Regardless, the whole idea is to not irradiate the hippocampus so no memory issues occur.

Finally, there is some discussion of foregoing PCI when no BM are present. In this instance, the literature suggests a comprehensive MRI surveillance program. If BM is detected, and hopefully, in small numbers and size; stereotactic radiotherapy (SRT) would be called for. Note that this paragraph was only discussed for extensive-stage SCLC. I chose to add it in case it might be of interest.

My wife's oncologist and radiologist have indicated that a PET scan and an MRI will take place soon after her 4th cycle of chemo. A decision will be made on whether to add 2 more chemo cycles. My hope is that there are no BM and the cancer in my wife's lungs are completely gone. PCI in relation to the above may get murky with variations of BM vs amount of cancer reduction (or progression).

I hope this information is of some use. At the very least, it should generate conversation with oncologists and radiologists.


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Excellent information Steve. I have not decided which way I come down on this issue. Luckily not something I have to decide right away (if ever). My main question to the doctors would be the efficacy of waiting for the Mets to show up and doing SBRT (obviously targeted) instead.

I have been reading old posts starting back in 2003. Reading the SCLC forum looking for LCNEC examples and the intro forum. PCI was a very active discussion subject in the mid 2000's. About a 50 50 split on if it should be done or not. Some positive outcomes and some nasty ones as well 

Thanks for sharing


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