2019年9月26日 星期四

三維適形放射(3D-Conformal)技術及調強適形放射治療



三維適形放射(3D-Conformal)技術及調強適形放射治療
(Intensity-Modulated Radiotherapy IMRT)

直至上世紀九十年代,隨著電腦技術的發展,劑量計算可以倚賴電腦進行。另一方面,電子機械技術的進步,三維斷層電腦掃瞄 ( CT Scanning ) 流行,促成新的放射治療機器與技術的進展。

三維適形放射治療能將較大劑量的輻射準確地射向腫瘤,同時對附近正常組織的破壞減到最少。治療前,病人需要接受電療設計專用的電腦掃描,其數據會匯入特定的劑量運算電腦,讓臨床腫瘤科專科醫生以三維空間影像審視腫瘤位置,將腫瘤和附近最可能受影響的淋巴組織,及鄰近重要的器官準確定位。隨後,醫生、放射治療師或醫學物理學家利用電腦協助,用不同放射束的入射角度及劑量比例,以設計最佳的電療方案。

至於調強適形治療,是在三維適形放射治療基礎上演進而來。在每個放射束(照射野)內分為許多子野,子野的放射強度是不一樣的(故稱為調強)。過程中劑量的計算,採用逆向設計治療計畫,全部由電腦負責,使腫瘤劑量適形性更好,特別對於不規則形腫瘤或腫瘤附近有重要組織器官需要保護的病例,調強適形放射治療比三維適形放療有更好的優勢。

以上為鼻咽癌治療的劑量分佈圖為例,二維和三維適形治療的高劑量區未能很好地覆蓋目標腫瘤區堿(紅色部份),而二維治療中,腮腺受到很高的劑量,而調強適形治療既能將高劑量準確地投放在目標腫瘤區堿,也能減少腮腺的劑量。

調強適形放療主要適合於前列腺癌、鼻咽癌、頭頸癌、甲狀腺癌、腦癌、乳腺癌、肺癌、胰腺癌等。應用調強適形放射治療能夠進一步提高腫瘤內劑量,降低附近正常組織的劑量,提高療效,減少副作用和後遺症,提升病人治療後的生活質素。如調強適性放射治療前列腺癌,可使病灶劑量由68Gy提高到81Gy,3年控制率由48%提高到94%,直腸副作用由57%降為2%;調強適形治療鼻咽癌可保護腮腺避免口乾,對於接近眼睛或視神經的鼻咽瘤,則能避免輻射線對視力的影響。






參考資料: http://www.cancerdoctor.hk/radiotherapy-technology.html
以上所提供的資訊僅作為教育及參考用途,如果你有任何醫療問題,
應向自己的腫瘤科專科醫生查詢,而不應單倚賴以上提供的資料。

2019年9月19日 星期四

How blending Western and traditional Chinese medicine can boost cancer treatment in Hong Kong

When his doctor told him that the sharp pain in his back was stage four lung cancer, Rocky Yiu, 57, could not bring himself to ask how long he had left to live. “It felt pointless asking because they practically gave me a death sentence,” he says.

Five years on, Yiu’s battle continues, aided by traditional Chinese medicine (TCM), which he believes has helped slow the spread of the disease.

The number of people diagnosed with cancer in Hong Kong is increasing every year, partly due to an ageing population. In 2016, according to the Hong Kong Cancer Registry under the Hospital Authority, 31,468 new cancer cases were diagnosed locally, while 14,209 Hongkongers lost their lives to the city’s No 1 killer.

Medical experts believe that, when used correctly, TCM might be more ideal than Western treatments for some, and it can play a complementary role in treating the condition for others. This has led to calls for more collaboration involving both forms of medicine.

Although Yiu had received 25 rounds of electrotherapy, nine months’ worth of targeted therapy and four cycles of chemotherapy, all failed to shrink the tumour in his lung.

By the time he completed the fourth cycle of chemotherapy, the tumour had grown from 5cm to 8cm. Yiu stopped all Western medical treatment, but continued with TCM, which he had been using to manage the side effects of the cancer treatment.

“Targeted therapy left my skin so sensitive that I couldn’t use warm water in the shower, not even during winter. TCM helped reduce the sensitivity, and also helped me manage the pain, constipation and tingling sensations from Western treatments,” he says.

During a check-up in 2016, six months after he discontinued chemotherapy, his doctor noticed that the growth had shrunk back to 5cm. Yiu credits TCM with the good news.

Although his prognosis still looks bleak – the cancer has spread, causing him pain in his bones and constipation – he says TCM has kept the more dire consequences of his illness in check.

Yiu’s TCM practitioner Tina Lee, who works at Tung Wah Hospital, says that because his cancer was advanced, her treatment plan was to help him improve his quality of life, and to counter some of the toxins left from the chemotherapy and targeted therapy.

“TCM is about promoting overall health, disease prevention, and boosting the body’s ability to heal to achieve harmony and balance,” Lee explains.

“But TCM has its limitations. We can’t determine whether a person has cancer just by taking their pulse or asking them a few questions. Patients are always diagnosed by Western medical methods, such as blood tests, biopsies and scans.”

Dr Liu Yulong, principal lecturer at the Baptist University’s School of Chinese Medicine, adds: “We wouldn’t encourage patients to rely solely on TCM for cancer, unless they are very old or too weak to endure conventional cancer treatments, such as chemotherapy.”

Liu says TCM could help some patients complete their Western treatment as planned. “TCM can help them manage their side effects so they can finish their cycles on time, which is essential to recovery.”

Dr Chan Leung-cho, a specialist in clinical oncology, agrees. He says TCM can help relieve nerve problems and dry mouth resulting from chemotherapy.

Chan and Liu both practise at the Hong Kong Anti-Cancer Society Dr and Mrs Michael S.K. Mak Integrated Chemotherapy Centre, which has been offering integrated Chinese and Western services since 2012. Both doctors have served some 400 patients.

Chan believes clear and direct communication between TCM practitioners and doctors is key to designing a successful integrated treatment plan for patients.

“Doctors of Western medicine are often worried something might go wrong if their patients also take TCM because they don’t know much about it – I don’t either. And patients may not be able to properly convey the kinds of treatment they’re undergoing.”

While Chan warns that patients can run serious risks if they withhold information about their TCM treatment from doctors, both he and Liu agree that Hongkongers could benefit from more direct collaboration between TCM and Western medicine.

In 2014, the Food and Health Bureau launched the Integrated Chinese-Western Medicine Pilot Project to study the operations at government hospitals.

The findings of the programme would help officials formulate the model for the city’s first Chinese medicine hospital, which is expected to open in late 2024.

“We want to show patients that integrated medicine can help them, and convince sceptical Western doctors that TCM can help their patients.

“It’s not about choosing sides, but what we can do for patients,” Liu says.

Yiu’s TCM practitioner Lee says she thinks this could also help patients identify trustworthy TCM practitioners, instead of turning to expensive and unlicensed healers.

“On the mainland, there are many hospitals with integrated Western and Chinese medical services. I think Hong Kong should follow its example.”

As for Yiu, he is trying to find hope in the time he has left.

“Sometimes I get better, which gives me hope. Then the pain comes back. I know it’s too much to ask for a miracle. All I can do now is treat every day as a reward.”









Reference information: South China Morning Post
The information aims to provide educational purpose only. Anyone reading it should consult Oncologist before considering treatment and should not rely on the information above.

2019年9月11日 星期三

大腸癌徵兆易被忽略

早期大腸癌通常沒有症狀,到了第二、三或四期癌症,患者才會因為出現徵兆而求醫。不過,大腸癌的症狀並不明顯,常被誤為便秘或痔瘡而被忽略。如腫瘤位於直腸,靠近肛門,便會有大便帶血或大便有黏液的情況;若腫瘤距離肛門較遠,患者或只感到腹痛。倘若癌細胞已轉移到肝臟,患者便會常感疲倦,並有黃疸、貧血及氣喘等症狀。因此,如身體突然出現變化,便應及早求醫;另外,接受大腸癌檢查亦有助於早期確診。


進行手術將腫瘤切除是根治大腸癌的最佳方法;部份第四期已轉移到個部分肝臟的患者亦可接受手術。不過,三期大腸癌患者於手術後,仍有四成至六成復發風險,須接受化療輔助。若確診時已達四期,不宜進行手術,便會使用化療加標靶藥物作治療。患者必須先進行KRAS/NRAS基因測試,如無基因變異,便可使用抗表皮生長因子(EGFR)標靶藥。如有基因變異,則只能採用抗血管生長標靶藥。


抗血管生長標靶藥可抑制腫瘤細胞增生血管的路徑,從而切斷營養供應;上一代抗血管生長標靶藥可阻截VEGF-A路徑生長,新一代的藥物則能同時阻截VEGF-A、VEGF-B和PLGF三個路徑,可更有效抑制癌症生長。美國國立綜合癌症網路(NCCN)已將新一代抗血管生長標靶藥納入標準二綫治療中,現時香港已可使用。


臨床腫瘤科專科醫生陳亮袓









參考資料: 智富雜誌
以上所提供的資訊僅作為教育及參考用途,如果你有任何醫療問題,
應向自己的腫瘤科專科醫生查詢,而不應單倚賴以上提供的資料。

2019年9月5日 星期四

首款獲批毋須接受生物標記測試 復發性卵巢癌維持治療新突破

卵巢是女性的重要生殖器官,雖然大小只有2至4厘米,卻掌管了女性荷爾蒙分泌和生育能力,說是女性的「大本營」並不為過。然而,當有不速之客,例如癌細胞入侵大本營,女士們便要面對卵巢癌這場硬仗。

卵巢癌是常見的婦科惡性腫瘤之一。最新統計數字顯示,目前卵巢癌位列本港女性常見癌症第六位,死亡率則位居第七。2016年發病個案為598宗,死亡個案為229宗。換句話說,約三分二患者能夠戰勝卵巢癌,三分一患者最終因卵巢癌而致命。

發現往往屆中晚期

迄今為止,卵巢癌並無理想的篩查方法。所謂篩查,是指在未出現任何症狀之前及早識別和診斷,提高治癒機會,減低死亡率。卵巢癌不像子宮頸癌可透過抹片有效篩檢,而癌指標CA125水平容易受其他身體狀況影響,故其靈敏度和特異性有限。另一方面,早期卵巢癌幾乎沒有症狀,直至患者因尿頻、腹脹、消化不良和食慾不振等症狀求醫時,病情往往已屆中晚期,增加治療的難度。

卵巢癌的特性是生長速度快,手術是重要的治療方法,化療則按個別需要在術前或術後給予,標準用藥為紫杉醇和卡鉑,療程每隔3星期一次,患者多數需接受6個療程。大部分卵巢癌個案對化療的反應不俗,惟中晚期卵巢癌復發率高達六成以上,這是由於肉眼看不見的微量癌細胞已在腹腔遊走,化療未必能完全將之消滅。因此,如何及早發現卵巢癌並有效防止復發,一直是臨床上的大難題。

以往,臨床上見過不少患者在熬過辛苦的化療後,癌細胞在短時間內死灰復燃,在別無選擇的情況下,只能再次接受化療,不但身心俱疲,更甚的是病情受控的時間亦愈來愈短,惟化療毒性較強,不宜長期使用。如何使化療的藥效維持更長時間?醫學界由此衍生出「維持治療」的概念,希望利用毒性較低的藥物控制腫瘤,讓患者在保持生活質素的大前提下帶病延年。

第一種應用於卵巢癌維持治療的藥物是透過靜脈滴注的抗血管新生標靶藥「貝伐珠單抗」(Bevacizumab)。所謂「三軍未動,糧草先行」,貝伐珠單抗的作用是抑制新血管的增生,藉此截斷癌細胞的養份供應,使其無法生長。換句話說,即是使癌細胞「斷糧」,無力再靜極思動,壯大聲勢。

令癌細胞無法修復

近年,醫學界研發出另一種新「武器」:PARP抑制劑。PARP是一種蛋白,作用是修復細胞DNA損傷。古語有云:「一鼓作氣,再而衰,三而竭。」完成鉑類化療後病情成功受控的患者,由於癌細胞DNA被化療破壞,若在此時乘勝追擊用藥抑制其修復功能,就可以控制病情。簡而言之,原理是令癌細胞「回唔到氣」,繼而自我萎縮及凋亡。

目前本港可用的兩款PARP抑制劑包括於2016年註冊的「奧拉帕尼」(Olaparib)和於2018年註冊的「尼拉帕利」(Niraparib),兩者均為口服藥物。兩者療效和副作用相若,普遍是疲倦和可控的血球數量下降。而尼拉帕利的突破之處,是適用對象更廣泛,乃第一款美國食品及藥物管理局(FDA)核准毋須接受BRCA基因測試也可採用的PARP抑制劑。

大型臨床研究證實,具BRCA基因突變的患者服用尼拉帕利作維持治療,無惡化存活期由5.5個月延長至21個月;沒有 BRCA基因突變的患者也呈雙倍增長,由3.9個月延長至9.3個月。由於在控制病情、延緩復發及降低死亡風險三方面均具顯著的臨床效益,美國國家綜合癌症網絡(NCCN)及英國國家健康暨臨床卓越研究所(NICE)已將尼拉帕利納入治療指引,是復發性卵巢癌維持治療的突破性進展。尼拉帕利每顆膠囊為100毫克,對醫生而言便於調校劑量;對患者而言便於用藥,只需每天口服一次,亞洲人通常每次兩顆膠囊,減低漏服藥物的機會。


個案分享

年約60歲的黃女士(化名)確診第三期卵巢癌,手術後接受化療和抗血管新生標靶治療,惟腫瘤受控僅18個月便復發。黃女士經檢測證實並無出現BRCA基因突變,遂接受第二線化療,這次僅相隔半年,癌細胞便再度肆虐。陳醫生為她處方PARP抑制劑,用藥至今已7個月,期間幾乎全無副作用,病情亦成功受控。

最後,女士們如出現持續腹部不適或消化不良,未必是腸胃問題,及早求醫方為上策。

陳亮祖醫生_臨床腫瘤科專科










參考資料: 信報
以上所提供的資訊僅作為教育及參考用途,如果你有任何醫療問題,
應向自己的腫瘤科專科醫生查詢,而不應單倚賴以上提供的資料。