本帖最後由 goodcat1111 於 2009-5-7 22:52 編輯
作者：Nick Mulcahy
出處：WebMD醫學新聞
April 21, 2009 — 甲狀腺癌病患的放射線曝露，包括健康照護場所如乳癌和痤瘡治療時的曝露，會比那些同樣有此疾病但無類似曝露者的預後差。
資深作者、多倫多Mount Sinai醫院耳鼻喉科主任Jeremy L. Freeman醫師等人寫道，已知放射線曝露是甲狀腺癌的一個風險因素，本研究登載於4月的頭頸外科和耳鼻喉期刊。
不過，之前的甲狀腺癌病患研究顯示，曝露於放射線者和未曝露者之間的臨床結果沒有差異。
新研究回溯回顧125名Mount Sinai醫院病患的放射線曝露情形，並和沒有曝露的其他574名Mount Sinai醫院病患資料進行比較。
Freeman醫師等人發現，相較於沒有曝露的病患，曝露於放射線的病患比較可能有第IV期疾病，因此有遠端轉移(9% vs 2%)、以及死亡(4% vs 1.5%) ，研究者表示，這和之前的研究報告相反。而且，曝露組的病患有較多人接受全部或幾乎全部的甲狀腺切除術(83% vs 38%)。再者，曝露組的病患有較多人需要額外的手術(23% vs 2%)，這也和之前的發現不同。
作者寫道，就我們所知，目前的研究是首次認為曝露於放射線的病患有較差的結果，作者認為，本研究有相對較多的曝露組病患，因而獲得與其他研究不同的結果。
作者寫道，相較於未曝露組，曝露組病患的腫瘤病理比較末期，較多病灶(63% vs 36%) 與甲狀腺外擴散(26% vs 8%)。
作者寫道，本研究的多數病患(56%)曾經因為對頭頸部之直接體外放射線治療而曝露於放射線，通常是治療良性狀況的放射線治療，如痤瘡。
Freeman醫師向Medscape Oncology表示，在1950到60年代，有許多人使用放射線治療痤瘡、甲腺狀腫大、黴菌感染與其他狀況。這些病患在後來因而付出代價。
第二常見的曝露類型(23%)是職業/診斷方面的，包括未保護的放射技術員、牙科助理、重複進行頭頸部造影的病患。Freeman醫師表示，這組也包括沒有離開放射室或保護不佳的螢光鏡技術員、牙科與x光技術員。在1950至60年代，並不瞭解這些曝露的複雜程度。
有11%病患屬於環境曝露(包括車諾比事件)；身體其他部位之直接體外放射線者佔6%。
【頭頸部的放射線治療傷害最大】
作者寫道，多數細胞分化良好的甲狀腺癌病患有好的疾病特定結果。的確，在這些平均追蹤10.6年的放射線曝露病患中，多數病患(86%)存活且在最後追蹤時沒有疾病。
不過，為了探究之前的放射線曝露類型是否會對腫瘤病理發現或臨床結果有影響時，研究者根據曝露類型將病患分成幾個小組。
這些小組比較曝露時的年紀、癌症分期、MACIS (轉移、年紀、切除的完整度、侵犯、腫瘤大小)評分、局部復發、遠端轉移、因疾病死亡的可能性。
特別的是，頭頸部直接體外放射曝露佔全部第IV期病患的56%，全部病患有60%的MACIS 評分大於8。此外，這小組有63%病患發生過局部復發、55%遠端轉移、80%死於甲狀腺癌。這一組病患數也是最多的。
另外，和其他小組相比，這小組病患的放射線曝露是在更年輕的年紀(平均年紀14.9歲) (P< .005)，除了職業或診斷性曝露者之外(平均年紀19.9歲)。Freeman醫師表示，這一組頭頸部曝露年紀較輕大多是因為治療痤瘡。
研究者宣告沒有相關財務關係。
Radiation Exposure, Including in Workplace, Worsens Outcome in Thyroid Cancer
By Nick Mulcahy
Medscape Medical News
April 21, 2009 — Thyroid cancer patients with exposure to radiation — from healthcare workplaces, for example, or treatments for conditions such as breast cancer and acne — appear to have worse outcomes than patients with the disease and no exposure.
"Radiation exposure is a well-established risk factor for thyroid cancer," write the study authors, led by senior author Jeremy L. Freeman, MD, otolaryngologist-in-chief at Mount Sinai Hospital, in Toronto, Ontario, in a study published in the April issue of the Archives of Otolaryngology — Head and Neck Surgery.
However, previous studies of thyroid cancer patients have shown no difference in clinical outcome between those exposed to radiation and those not exposed.
The new study retrospectively reviewed 125 Mount Sinai patients with radiation exposure and compared them with a database of 574 Mount Sinai patients with no exposure.
Dr. Freeman and colleagues found that, compared with patients with no exposure, radiation-exposed patients were more likely to have stage?IV disease, and thus distant metastases (9% vs 2%), and to have died (4% vs 1.5%) — which is in contrast to previous reports comparing the 2 groups, say the authors. Also, more exposed patients underwent total or near-total thyroidectomy (83% vs 38%). Further, more of the exposed patients required additional procedures (23% vs 2%), which is also in contrast to previous findings.
"To our knowledge, the present study is the first to suggest worse prognosis in radiation-exposed patients," write the authors, who speculate that the relatively large number of exposed patients in the study might account for the differences with other research.
The present study is the first to suggest worse prognosis in radiation-exposed patients.
The tumors of radiation-exposed patients also had more aggressive pathology, write the authors, with more multifocal disease (63% vs 36%) and extrathyroid spread (26% vs 8%) than patients without exposure.
Most of the patients in the study (56%) had exposure to radiation from direct external radiotherapy to the head and neck, "often as therapeutic radiography to treat benign conditions," such as acne, write the authors. "A whole bunch of people in the 1950s and 60s were given radiation for acne, adenoids, fungal infections, and other conditions," Dr. Freeman told Medscape Oncology. "The people who received that radiation are paying for it in later life," he said.
A whole bunch of people in the 1950s and 60s were given radiation for acne, adenoids, fungal infections, and other conditions.
The second-most common type of exposure (23%) was occupational/diagnostic, which includes unprotected radiography technicians, dental assistants, and patients who had repeated imaging of the head and neck. "The people in this group include technicians who ran fluoroscopes and dental and x-ray technicians who did not leave the room or wear protection," said Dr. Freeman, who explained that the state of the art in the 1950s and 1960s did not understand the ramifications of these exposures.
Environmental exposure (including the accident at Chernobyl) accounted for 11% of the patients. Direct external radiotherapy to another body site, such as the breast, accounted for 6%.
Radiotherapy to Head and Neck Most Damaging
Most patients with well-differentiated thyroid cancer have good disease-specific outcomes, write the authors. Indeed, even among these radiation-exposed patients, who were followed for a mean of 10.6 years, most patients (86%) were alive and free of disease at last follow-up.
However, in an effort to determine whether the type of previous radiation exposure had an effect on tumor pathologic findings or clinical outcome, the researchers divided the radiation-exposed patients into subgroups according to type of exposure.
These subgroups were compared for age at exposure, cancer stage, MACIS (metastasis, age, completeness of resection, invasion, and size of tumor) score, local recurrence, distant metastases, and likelihood of death from disease.
Notably, the subgroup exposed to direct external radiotherapy to the head and neck accounted for 56% of all patients with stage?IV disease and 60% of all patients with MACIS scores higher than 8. Also, this subgroup accounted for 63% of patients who experienced local recurrence, 55% of those with distant metastases, and 80% of those who died of thyroid cancer. This patient subgroup also had the most patients.
Also, these patients had radiation exposure at a statistically significant younger age (mean age, 14.9 years) than each of the other subgroups (P?< .005), except the group exposed either occupationally or through diagnostics (mean age, 19.9 years). "The young age here probably largely represents treatment for acne," said Dr. Freeman about the head and neck subgroup.
The researchers have disclosed no relevant financial relationships.
Arch Otolaryngol Head Neck Surg. 2009;135:355-359. |
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