SNM 2009:檸檬汁降低腮腺吸收的放射線


  July 2, 2009 (多倫多) — 間歇性給予檸檬汁可以降低接受碘-131(I-131)治療之甲狀腺癌病患的放射線吸收。這些發現發表於核子醫學會第56屆年會中的壁報。
  
  主要研究者、華盛頓特區華盛頓醫院中心核子醫學主任Douglas Van Nostrand醫師解釋,醫師試圖藉由使腮腺的放射線吸收降到最低,來保留接受甲狀腺癌治療之病患的唾腺功能。
  
  Van Nostrand醫師解釋,這是放射線治療界的主要考量,如何在甲狀腺癌的放射碘治療中保護唾腺功能。
  
  他解釋,一項實務做法是,給予檸檬水果糖或糖球,以刺激甲狀腺癌病患的唾腺,目標為降低唾腺的放射線曝露。Van Nostrand醫師向Medscape Radiology表示,我們根據經驗這樣運作,也教導住院醫師這麼做。
  
  不過,發表於2005年的一篇報告,駁斥上述論點且提出,這種做法反而會增加唾腺的放射線曝露,增加唾腺的放射碘吸收,讓病患產生更多副作用。
  
  Van Nostrand醫師指出,該報告建議使用刺激唾液分泌劑,至於檸檬汁、檸檬水果糖、酸味糖果,則在碘-131治療後24小時內避免給予病患。
  
  他表示,有些機構遵照這個建議,有些則沒有。他的分析即在探討此建議的效度。
  
  Van Nostrand醫師等人回溯回顧在碘-131治療前進行臨床腮腺掃描的甲狀腺癌病患的資料。之後給予口服放射碘,2小時之後開始讀取影像。5分鐘之後給病患檸檬汁。影像讀取時間1小時。之後重覆此步驟(第2期)。
  
  評估29名病患;6人顯示無明顯的放射碘活性,因而未納入分析中。研究者獨立評估其他的23名病患(11名男性與13名女性)、共46個腺體。病患平均年紀為49歲。研究者在46個腺體中的35個(89%)偵測放射碘活性。
  
  研究者確認給予檸檬之前的放射線活性失敗百分比、放射碘失敗最低點的時間、放射碘累積到相當於給予檸檬汁前1小時的時間、第1期和第2期時腮腺的放射線吸收劑量變化百分比。
  
  研究者發現,第1期和第2期的平均失敗率為84%和83%。放射碘再度累積至相當於給予檸檬汁之前放射碘活性的平均時間,第1期為17分鐘、第2期為35分鐘。
  
  Van Nostrand醫師表示,此一臨床訊息為,依據給予的時間,檸檬汁可降低腮腺的放射線吸收量達38%至51%。
  
  他表示,病患需立即給予檸檬水果糖。藉此,可降低碘在唾腺的期間。這可降低放射線劑量,降低放射線傷害、疼痛、腫脹與口乾的頻率。
  
  與會的物理學家、紐約市Sloan Kettering紀念癌症中心的Pat Zanzonico博士表示,根據Van Nostrand醫師團隊的研究,給予檸檬汁是可以保留唾腺功能的「無害的」治療方式。
  
  Zanzonico博士表示,這是有趣且病患容易接受的方法,可使甲狀腺癌放射碘治療的嚴重問題最小化;也就是說,使曝露於放射線導致的唾腺和唾液功能損失最小化。
  
  你可以減少唾腺曝露的放射線劑量達51%,腺體和腺體功能或許可以有所保留。
  
  他表示,如果真如研究認為的這麼簡單且有效,病患將可容易接受。病患一般會因為放射碘治療而感到痛苦和失去唾腺功能。這個方法將可改善病患的整體感覺。
  
  本研究為獨立進行。Van Nostrand 醫師和Zanzonico博士宣告沒有相關財務關係。
  
  SNM 2009 年會:摘要1298。發表於2009年6月15日。
  

SNM 2009: Lemon Juice Reduces Radiation Exposure to Parotid

By Louise Gagnon
Medscape Medical News

July 2, 2009 (Toronto, Canada) — Intermittent administration of lemon juice can decrease the absorption of radiation for patients with thyroid cancer who are undergoing treatment with iodine-131 (I-131). Those findings were presented in a poster presented here at the 56th annual meeting of the Society of Nuclear Medicine.

Principal investigator Douglas Van Nostrand, MD, director of nuclear medicine at Washington Hospital Center in Washington, DC, explained that clinicians have made attempts to preserve salivary gland function through minimizing radiation absorption to the parotid glands in patients receiving treatment for thyroid cancer.

"It's a major concern within the radiation therapy community, regarding how one protects salivary glands from radioiodine that you are treating the thyroid cancer with," explained Dr. Van Nostrand.

One practice has been to administer lemon drops or a candy drop to stimulate salivation in patients with thyroid cancer with the goal of reducing radiation exposure to the salivary glands, he explained. "We had been doing this practice empirically, passing it down from faculty members to residents," Dr. Van Nostrand told Medscape Radiology.

A report published in 2005, however, refuted that notion and put forth, paradoxically, that the practice was causing increased radiation exposure to the salivary glands and increased uptake of radioiodine by the salivary glands, thereby producing more adverse effects in patients.

It was recommended in that report that the use of sialogogues, in the form of lemon juice, lemon candies, and sour candies, be avoided in patients 24 hours after I-131 treatment, noted Dr. Van Nostrand.

"Some institutions follow this recommendation, and some do not," he said. His analysis explored the validity of this recommendation.

Dr. Van Nostrand and colleagues retrospectively reviewed data on thyroid cancer patients who had received a clinical parotid gland scan before I-131 therapy. Oral radioiodine was then administered, and images were initiated 2 hours after that point. Patients were given lemon juice 5 minutes later. Patients were imaged for 1 hour. This process was then repeated (phase 2).

Twenty-nine patients were evaluated; 6 showed no demonstrable radioiodine activity and were not included in the analysis. Investigators independently assessed the remaining 23 patients (11 men and 13 women), or 46 glands. The mean age of patients was 49 years. Researchers detected radioiodine activity in 35 (89%) of 46 parotid glands.

Investigators determined the percentage washout relative to pre–lemon juice radioiodine activity, time to nadir of washout of radioiodine, time to reaccumulation of radioiodine to pre–lemon juice activity at 1 hour, and percentage change in radiation absorbed dose to the parotid glands in phase 1 and phase 2.

Researchers found that the mean washout was 84% and 83% in phase 1 and phase 2, respectively. Mean time to reaccumulation of radioiodine activity equivalent to the level of radioiodine activity pre–lemon juice was 17 minutes in phase 1 and 35 minutes in phase 2.

The clinical message, said Dr. Van Nostrand, is that lemon juice may decrease the amount of radiation absorption to the parotid glands by anywhere from 38% to 51%, depending on time of administration.

"[Patients] need to take lemon candies sooner rather than later," he said. "By doing that, they decrease the duration of iodine in the salivary glands. That reduces the radiation dose, and that reduces the frequency of radiation damage, pain, swelling, and resulting dry mouth."

The administration of lemon juice is an "innocuous" treatment that appears to spare salivary function, according to Dr. Van Nostrand's team's research, said Pat Zanzonico, PhD, an attending physicist at Memorial Sloan Kettering Cancer Center in New York City.

"It is an interesting and patient-friendly approach to minimize a significant problem in radioiodine treatment of thyroid cancer; namely, a loss of saliva and salivary function secondary to radioiodine exposure," said Dr. Zanzonico.

"You can get up to a 51% reduction in the radiation dose to the salivary glands, and presumably there would be some sparing of the glands and retention of the function of the glands.

"If it's as simple and effective as this research suggests, patients would appreciate this very much," he said. "They typically get pain and loss of production of saliva with radioiodine treatment. It would improve the patient's overall experience."

The study was independently conducted. Dr. Van Nostrand and Dr. Zanzonico have disclosed no relevant financial relationships.

SNM 2009 Annual Meeting: Abstract 1298. Presented June 15, 2009.

J Nuclear Med. 2009;50:249.

    
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